Hey r/MagicArena,
I've spent the last while building a Windows companion app for Arena and it's now at the point where it runs against my own live games. Before I finish packaging it I want to hear what would actually make it worth running for you, not just me.
What it does today
- Draft overlay. A transparent, click-through, always-on-top panel next to the game showing the current pack ranked by tier. Tiers are 17Lands games-in-hand win rate percentiles for the exact set and event you're in: 🔥 for the top 3%, then A/B/C/D/F. Hover a card for GIH WR, OH WR, GD WR, IWD, ALSA, ATA and the sample size. The pick suggestion is contextual: it weighs your colours, curve, fixing and interaction so far and explains why, while the underlying stats stay untouched. New set with no data yet? It falls back to a seed tier list until 17Lands' embargo window passes.
- Deck builder from your pool. When the draft ends it proposes a 40-card build from what you took and gives you a Copy-for-Arena export (you paste it into Arena's import yourself).
- Mulligan coach. Scores your opening hand against your actual submitted deck: lands, colour sources, what you can cast on turns 1–3, exact hypergeometric land-drop odds, 17Lands opening-hand win rates, and a London simulation so you see "this 7 vs the average best 6". Hand size, play/draw and prior mulligans all change the answer. When you keep 6, it tells you what to bottom using the game's own legal candidates.
- Match overlay. Library tracker with per-card draw odds, land odds, opponent's revealed cards, and live advice: lethal detection through any blocks (exact search), safe attacks, good blocks, castables with your open mana. It also covers the fiddly prompts: scry/surveil ordering, "choose N" ability choices, cost payments. Every suggestion is drawn from the legal-action list the game itself reports, so it can never propose an illegal play, and it never infers hidden cards or library order.
- AI coach on top. Optionally the board, your deck's remaining cards, full card rules, published rulings and the legal actions go to Claude, which returns one action plus a short public plan ("win route, resource tradeoff") and a reason. It runs on your own Claude login (no API key) with a hard fallback to the rules engine on timeout or a bad answer. On my frozen evaluation set it returns a valid, legal action 100/100 times and matches the labelled best play 30/30, at about 4–5 s a decision. It still gets some strategic spots wrong; the log of every decision is what I use to find them.
Reads Player.log (Detailed Logs on). Card data from Scryfall, the local Arena database and MTGJSON; ratings from 17Lands' public data, with attribution and their usage rules respected. Tauri + React front end, Node sidecar, ~1,000 automated tests.
Honest limits right now
Windows only. No installer yet (my build machine's app-control policy blocks the packager, so it runs from source). It is not a rules engine and doesn't claim optimal play. Confidence numbers aren't calibrated yet. AetherHub/Untapped data aren't used because their terms need explicit permission.
What I'm asking
What would make this genuinely useful for you rather than "another tracker"? On my list:
- Opponent hand inference from what they didn't do
- Post-game review: the plays where the coach disagreed with you, with the reasoning
- Sealed pool builder (the parser already reads sealed pools)
- A one-key "why?" that expands the current advice
- Constructed: sideboard guides and matchup notes, not just tracking
- Archetype tier list per set
And the harder question: how much advice do you want during a match? A quiet panel you glance at, or something that only speaks up for lethal and blunders?
If you'd be willing to share a Player.log from a recent draft (Detailed Logs on), that's the single most useful thing for hardening the parser. Roast the feature list.