Grail How to Beat the Day 10 Boss

Version 0.39 added a final boss on day 10 plus good and bad endings. That fight is still in the 1 September 2026 release. It is not the six-win scoreboard — hearts still track player-battle wins — but it is a separate check at the end of the clock. If you arrive on day 10 at three losses with fourteen cards, the boss is a formality. This page is how to beat it. Routing to get there is how to win a run.

What day 10 is

The day clock on the right of the overworld counts toward 10. Player battles still happen at the end of days. Six snapshot wins can happen before day 10; four losses can end the run before you see the boss. Treat the finale as extra, not as a replacement for the heart track.

Good and bad endings are the story payoff. Play for lives first. Read lore after the credits, not during a 40-turn stall.

Beating GRAIL with less than 5 cards

Checklist before the clock hits 10

• Lives: if you are at three player-battle losses, skip side quests even if they pay. A boss you never see is a boss you did not beat.
• Deck size: thinner than day 3, or at least not two shops fatter. Extra cards delay the engine. Energy and cards.
• Strip or over-heal: bleed and poison snapshots on the way in will chip you. Apple-style 10% strip and Mabel over-heal are how you enter the boss above panic HP. Status effects.
• One sentence: bleed chip, cheese poison, or gadget tax. Not “I will figure it out in the fight.” You cannot sideboard mid-combat. PvP battles taught that already.
• No waiting for Iconics: Rapier, roast, prosthetic are optional. Secret events are optional. The boss is not.

How the fight plays

Same rules as every other fight: four starting energy, one pip per draw turn, 40-turn stall damage, larger deck usually starts. The boss is a deck, not a click pattern. You watch. You already built.

If your cards sit unfilled, you will lose to the stall wall or to a status you cannot strip. Sell before day 10, not during. There is no sell button in the duel. Controls.

Bring a cycle-one play. Bosses that live to shuffle will punish fat poison plans if you are the one emptying discard. Bosses that chip will punish you if Toothpick never applied. Name the plan, then do not add a fourth 3-pip “just in case.”

Hero notes

Ratagnan wants cheap detonations. Upgrade Toothpick, not a souvenir sword. Mabel wants food that actually plays plus a poison half so over-heal is not a tall corpse. Zappy wants a gadget that fills on cycle one so shock has time to tax. Starter builds still apply on day 10. The boss does not ask you to invent a fourth kit.

Endings

Good versus bad is tied to how you got here: lives, cards you won with, lore flags. 0.39 did not publish a flowchart. This wiki will not invent one. Unlock pieces by winning with different cards, then take the finale with lives left. If you only care about the mechanical win, ignore the ending colour and count hearts.

After a wipe on day 10

Ask the same four questions as any loss: pips, status, HP from side quests, opponent thinner? Then change one thing on the next file. Do not rebuild the entire synergy checklist because a finale felt unfair. Snapshot PvP on day 9 is still the more common wipe.

When you can beat day 10 on Ratagnan, spend trophies. When you cannot, open the run planner on day 8 and skip a shop. The boss is a thin-deck exam with a story sticker on it.