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STS2 Subclasses Mod
by EGAAAAZv1
Pick your starter deck before each run — 22 archetype presets across all 5 characters, with 25 custom cards and 17 themed starter relics. Full JP / EN / zh-CN support, multiplayer-compatible, and built to feel native to STS2.
Created
Apr 13, 2026
Updated
Jun 6, 2026
Description
📢
Future updates will be released exclusively through the Steam Workshop. The Nexus Mods version will no longer be updated.
Please subscribe to the Steam Workshop version to receive the latest fixes and features:
https://steamcommunity.com/sharedfiles/filedetails/?id=3747829352
Follow me on X / Twitter: @Egaaaaz
💬 Community Discord
Bug reports, balance feedback, mod chat — all welcome. EN/JP both fine.
バグ報告・フィードバック・雑談歓迎、英日どちらも OK。
→ https://discord.gg/BjjAdjRdHz
Sts2ClassAbilities is out — the companion that adds preset-specific Ultimates and Tacticals to every starter deck in this mod. 36 signature moves, painterly per-cast cinematics, full multiplayer sync. Balance feedback welcome.
→ STS2 Class Abilities on Nexus https://www.nexusmods.com/slaythespire2/mods/656
Wiki (EN/JP): https://wikiwiki.jp/sts2_starter/
Note: the wiki may be updated ahead of the mod itself. Feel free to drop feedback in the comments section on any wiki page.
Last updated: v0.1.7 — 2026-04-26
What's new in v0.1.7
- Fixed MP issue: starter relics (PocketedSleeves, ScorpionStinger, AnvilShard) no longer misfire on the friend's character — they now compare by NetId/CombatId instead of object reference.
- Fixed MP desync: added wrappers on 6 transient relic flags (AshenHeart, AsteroidCore, IronCore, PocketedSleeves x2, RuggedGauntlet) so BaseLib's checksum routine includes them. Without these, host/joiner state hashes diverged whenever the flags ticked.
- Conductive Claw: removed the per-turn claw rebound effect — that mechanic now lives on the Claw Prime tactical in Sts2ClassAbilities v0.3.3 (gated on tactical usage rather than passive-on-relic).
Description
Supports in-game language localization in Japanese, English, and Simplified Chinese for UI text, preset labels, deck descriptions, and all custom card / relic text.
Sts2StartingDeckSelect lets you pick a starter deck preset for each character before a run begins. The goal is to add meaningful early-build choice while preserving the original game flow and overall balance feel.
Current content:
- 25 custom cards across all 5 characters
- 17 custom starter relics tuned to each preset archetype
- 21 starter deck presets total (3–5 per character — Ironclad / Silent / Regent / Necrobinder / Defect)
- Each non-vanilla preset is paired with a thematic starter relic swap for stronger identity
- Ascension effects (including Ascender's Bane on A5+) apply correctly on top of the chosen preset
The mod is built with multiplayer in mind and includes:
- Host-driven selection flow
- Synchronized preset state across all players
- Deterministic starter deck setup (no after-the-fact deck mutation) to avoid combat-start sync drift
- Safe fallback to the default starter deck when needed
It also ships with a polished deck-select UI and native-style card preview so you can read card text, cost, and type before starting. Upgraded values render in green on custom cards and relics, matching vanilla behavior.
Feel free to share which starter deck card lists feel fair, fun, or too strong.
Feedback is always welcome. If you spot balance issues, UI quirks, multiplayer sync bugs, or version-specific problems, drop a note in the Posts/Bugs tab. Screenshots, logs, mod list, and game version info help a lot.
Note on card and relic art
Custom card and relic artwork is currently AI-generated. I'm a solo dev and this was the fastest path to shipping playable content.
If you enjoy card / pixel / poster-style art and want to contribute replacement pieces — even one or two — I'd love to credit you in the mod. No deadlines, no strict scope, just a casual collab. Reach out via Posts here or the linked Reddit thread.
Installation
1. Install BaseLib v3.0.9 or later — required for save persistence and multiplayer state sync. Without BaseLib, run state will reset on save/load and multiplayer will desync.
2. Close Slay the Spire 2.
3. Download Sts2StartingDeckSelect-v0.1.7.zip from the Files tab.
4. Extract all three files into your STS2 mods folder:
- Sts2StartingDeckSelect.dll
- Sts2StartingDeckSelect.pck
- Sts2StartingDeckSelect.json
5. Start the game and confirm the mod is enabled in your mod list / loader.
6. Start a new run, choose a character, then pick a starter deck preset.
If you are updating from an older version, overwrite all three files with the new ones.
Note: the .pck file contains custom card / relic art and localization data. Without it, custom content will fail to display correctly.
Multiplayer note
All players in the lobby must run the exact same versions of Sts2StartingDeckSelect, Sts2ClassAbilities (if used), and BaseLib. Mismatched versions cause state checksum desync and disconnects (typical symptom: black screen at the Neow stage). Easiest way to coordinate is to share your full mods folder as a zip with the other player.
Main features
- Starter deck preset selection before run start (3–5 presets per character, 21 total)
- Per-character deck identity / archetype presets with matching starter relic swaps
- 25 custom cards + 17 custom starter relics, all localized in JP / EN / zh-CN
- Ascension-compatible: Ascender's Bane and other Ascension effects stack correctly on top of the preset
- Multiplayer-compatible selection flow with host sync and deterministic deck setup
- Deck preview panel with grouped card list and ×N count badges
- Upgrade values render in green (matches vanilla)
- Native-style card display for readable card info
- Default-safe behavior to reduce run-breaking edge cases
- UI improvements designed to match STS2's visual style
Requirements
- Slay the Spire 2 (currently verified on the beta branch — v0.104.0)
- BaseLib v3.0.9 or later
- A working STS2 mod environment / loader setup
If your local setup has additional loader or platform-specific requirements, please follow your normal STS2 mod setup steps.
Troubleshooting
If the deck selection UI appears but the selected cards do not apply correctly, please report:
- your Slay the Spire 2 game version
- your platform / OS
- your enabled mod list
- whether you are using any loader or dependency mods
- screenshots or logs if available
Common issues:
- Custom card art missing or text shows localization keys → the .pck file was not installed or is out of date. Re-copy all three files.
- Mod not detected → verify all three files are in the mods folder and the mod is enabled in your loader.
- Multiplayer disconnect at Neow / black screen → version mismatch between players. Confirm everyone has identical versions of all three mods (Sts2StartingDeckSelect, Sts2ClassAbilities if used, BaseLib).
This helps identify version mismatches, load-order issues, dependency conflicts, or possible platform-specific behavior.
Shout outs
Thanks to Mega Crit for Slay the Spire 2.
A very special thanks to MIJAMIJAMIJA, whose extensive testing, detailed feedback, bug reports, and design suggestions were a major help in shaping this release.
Huge thanks to the STS2 modding community for shared knowledge and tooling.
Thanks to everyone testing builds, reporting bugs, and sharing balance / UX feedback on Reddit and here. Your reports go straight into the updates.
Future updates will be released exclusively through the Steam Workshop. The Nexus Mods version will no longer be updated.
Please subscribe to the Steam Workshop version to receive the latest fixes and features:
https://steamcommunity.com/sharedfiles/filedetails/?id=3747829352
Follow me on X / Twitter: @Egaaaaz
💬 Community Discord
Bug reports, balance feedback, mod chat — all welcome. EN/JP both fine.
バグ報告・フィードバック・雑談歓迎、英日どちらも OK。
→ https://discord.gg/BjjAdjRdHz
Sts2ClassAbilities is out — the companion that adds preset-specific Ultimates and Tacticals to every starter deck in this mod. 36 signature moves, painterly per-cast cinematics, full multiplayer sync. Balance feedback welcome.
→ STS2 Class Abilities on Nexus https://www.nexusmods.com/slaythespire2/mods/656
Wiki (EN/JP): https://wikiwiki.jp/sts2_starter/
Note: the wiki may be updated ahead of the mod itself. Feel free to drop feedback in the comments section on any wiki page.
Last updated: v0.1.7 — 2026-04-26
What's new in v0.1.7
- Fixed MP issue: starter relics (PocketedSleeves, ScorpionStinger, AnvilShard) no longer misfire on the friend's character — they now compare by NetId/CombatId instead of object reference.
- Fixed MP desync: added wrappers on 6 transient relic flags (AshenHeart, AsteroidCore, IronCore, PocketedSleeves x2, RuggedGauntlet) so BaseLib's checksum routine includes them. Without these, host/joiner state hashes diverged whenever the flags ticked.
- Conductive Claw: removed the per-turn claw rebound effect — that mechanic now lives on the Claw Prime tactical in Sts2ClassAbilities v0.3.3 (gated on tactical usage rather than passive-on-relic).
Description
Supports in-game language localization in Japanese, English, and Simplified Chinese for UI text, preset labels, deck descriptions, and all custom card / relic text.
Sts2StartingDeckSelect lets you pick a starter deck preset for each character before a run begins. The goal is to add meaningful early-build choice while preserving the original game flow and overall balance feel.
Current content:
- 25 custom cards across all 5 characters
- 17 custom starter relics tuned to each preset archetype
- 21 starter deck presets total (3–5 per character — Ironclad / Silent / Regent / Necrobinder / Defect)
- Each non-vanilla preset is paired with a thematic starter relic swap for stronger identity
- Ascension effects (including Ascender's Bane on A5+) apply correctly on top of the chosen preset
The mod is built with multiplayer in mind and includes:
- Host-driven selection flow
- Synchronized preset state across all players
- Deterministic starter deck setup (no after-the-fact deck mutation) to avoid combat-start sync drift
- Safe fallback to the default starter deck when needed
It also ships with a polished deck-select UI and native-style card preview so you can read card text, cost, and type before starting. Upgraded values render in green on custom cards and relics, matching vanilla behavior.
Feel free to share which starter deck card lists feel fair, fun, or too strong.
Feedback is always welcome. If you spot balance issues, UI quirks, multiplayer sync bugs, or version-specific problems, drop a note in the Posts/Bugs tab. Screenshots, logs, mod list, and game version info help a lot.
Note on card and relic art
Custom card and relic artwork is currently AI-generated. I'm a solo dev and this was the fastest path to shipping playable content.
If you enjoy card / pixel / poster-style art and want to contribute replacement pieces — even one or two — I'd love to credit you in the mod. No deadlines, no strict scope, just a casual collab. Reach out via Posts here or the linked Reddit thread.
Installation
1. Install BaseLib v3.0.9 or later — required for save persistence and multiplayer state sync. Without BaseLib, run state will reset on save/load and multiplayer will desync.
2. Close Slay the Spire 2.
3. Download Sts2StartingDeckSelect-v0.1.7.zip from the Files tab.
4. Extract all three files into your STS2 mods folder:
- Sts2StartingDeckSelect.dll
- Sts2StartingDeckSelect.pck
- Sts2StartingDeckSelect.json
5. Start the game and confirm the mod is enabled in your mod list / loader.
6. Start a new run, choose a character, then pick a starter deck preset.
If you are updating from an older version, overwrite all three files with the new ones.
Note: the .pck file contains custom card / relic art and localization data. Without it, custom content will fail to display correctly.
Multiplayer note
All players in the lobby must run the exact same versions of Sts2StartingDeckSelect, Sts2ClassAbilities (if used), and BaseLib. Mismatched versions cause state checksum desync and disconnects (typical symptom: black screen at the Neow stage). Easiest way to coordinate is to share your full mods folder as a zip with the other player.
Main features
- Starter deck preset selection before run start (3–5 presets per character, 21 total)
- Per-character deck identity / archetype presets with matching starter relic swaps
- 25 custom cards + 17 custom starter relics, all localized in JP / EN / zh-CN
- Ascension-compatible: Ascender's Bane and other Ascension effects stack correctly on top of the preset
- Multiplayer-compatible selection flow with host sync and deterministic deck setup
- Deck preview panel with grouped card list and ×N count badges
- Upgrade values render in green (matches vanilla)
- Native-style card display for readable card info
- Default-safe behavior to reduce run-breaking edge cases
- UI improvements designed to match STS2's visual style
Requirements
- Slay the Spire 2 (currently verified on the beta branch — v0.104.0)
- BaseLib v3.0.9 or later
- A working STS2 mod environment / loader setup
If your local setup has additional loader or platform-specific requirements, please follow your normal STS2 mod setup steps.
Troubleshooting
If the deck selection UI appears but the selected cards do not apply correctly, please report:
- your Slay the Spire 2 game version
- your platform / OS
- your enabled mod list
- whether you are using any loader or dependency mods
- screenshots or logs if available
Common issues:
- Custom card art missing or text shows localization keys → the .pck file was not installed or is out of date. Re-copy all three files.
- Mod not detected → verify all three files are in the mods folder and the mod is enabled in your loader.
- Multiplayer disconnect at Neow / black screen → version mismatch between players. Confirm everyone has identical versions of all three mods (Sts2StartingDeckSelect, Sts2ClassAbilities if used, BaseLib).
This helps identify version mismatches, load-order issues, dependency conflicts, or possible platform-specific behavior.
Shout outs
Thanks to Mega Crit for Slay the Spire 2.
A very special thanks to MIJAMIJAMIJA, whose extensive testing, detailed feedback, bug reports, and design suggestions were a major help in shaping this release.
Huge thanks to the STS2 modding community for shared knowledge and tooling.
Thanks to everyone testing builds, reporting bugs, and sharing balance / UX feedback on Reddit and here. Your reports go straight into the updates.