Rotbloom the Sporeling, Devourer of Roots: how to beat

Rotbloom the Sporeling, Devourer of Roots — dungeon “The Blighted Sanctum (East Wing — Prison of the Ancients)”, level 39. The deck: phases, turn cycle,…

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Dungeon The Blighted Sanctum (East Wing — Prison of the Ancients), boss 2 of 4, level 39.

The boss plays its own deck: every turn it plays the next line of its phase’s cycle, with no randomness. Learn the cycle and you know what is coming. The numbers on this page are the same as in the card tooltip in combat: before Hardiness and Defender’s Stance. Mechanics in detail — Boss mechanics.

In short

Modes: Heroic (at level 60), Normal (at the place’s level, 36–46), Keystone +10 (Mythic+, at level 60).
2 phases, 6 cards in the deck. Schools: ☠ Poison 5, ⚔ Physical 1.
“Damp Cellar” cold: every enemy turn, everyone through shields — heroic 1,040, keystone +10 860 to each before Hardiness. No cold in normal mode.
“Big Slap” test strike — on boss turns 8 and 16: heroic 7,000, keystone +10 8,000; 40% weaker with a defensive card on yourself.
The heaviest hit is “Big Slap”: heroic 7,000, keystone +10 8,000.

Phases and turn cycle

The phase changes with the boss’s Health. In each phase the boss goes round its own cycle: at the end it starts again. The boss’s next turn shows on its portrait.

1. “Growing” — from the start of the fight

Down to 15% Health.

Cycle step	What the boss plays
1	☠ Wet Slap
2	☠ Wet Slap + ☠ Mould in the Air
3	☠ Wet Slap + ☠ Damp Bandages
4	☠ Wet Slap + ☠ Mould in the Air
5	⚔ Dried Up

2. “Last Exhale” — below 15% Health

Below 15%: in 3 turns she exhales on everyone, finish her.

On entering the phase the boss plays at once: ☠ Last Exhale.

Cycle step	What the boss plays
1	☠ Wet Slap + ☠ Mould in the Air
2	☠ Wet Slap + ☠ Mould in the Air
3	⚔ Dried Up

The “Big Slap” test strike is not part of the cycle: the boss announces it on its turns 7 and 15 and hits on turns 8 and 16.

Cards and numbers

The number is what a hit takes before Hardiness (through shields — from Health only), how much the boss heals itself, the shield it puts up, a minion’s Health. A dash means the card is not in that mode or has no number. Keystone: +10 numbers; hits are the same from +7 to +9 and weaker per level below +7.

Card	What it does	Heroic	Normal	Keystone +10	How to answer
☠ Big Slap · Poison, test strike	A test strike on whoever holds the boss’s attention (usually the tank). The boss announces it on its own, outside the cycle, and hits on its 8th and 16th turn; one turn before, there is a countdown on the portrait and a warning above your hand. The target plays a defensive card on themselves before the hit — it is 40% weaker. Not in normal mode. Through shields.	7,000 · with a defensive card 4,200	—	8,000 · with a defensive card 4,800	Test strike, one turn of warning. The tank plays a defensive card, the healer tops him up in advance.
☠ Wet Slap · Poison, hit	A hit on whoever holds the boss’s attention (usually the tank).	2,350	600	4,100	A plain hit.
☠ Mould in the Air · Poison, stacking damage over time	Damage over time on everyone that stacks: each play adds a stack, up to 5. The number is per turn per stack; a stack lasts 5 turns.	106 per turn per stack	18 per turn per stack	123 per turn per stack	On everyone, builds up, wears off by itself. Party healing; a cleanse, if you have one, makes it easier.
☠ Damp Bandages · Poison, weaker healing for all	The whole party is healed ×0.5 for 3 turns.	—	—	—	For 2 turns healing on everyone is halved. Shields now, strong healing later.
⚔ Dried Up · Physical, opening: more damage to the boss	The boss is open: damage to it ×1.3 for 2 turns.	—	—	—	+30% damage for 1 party turn.
☠ Last Exhale · Poison, charge	A charge: in 3 turns it hits everyone, the number is for each. Shields hold half, ignores 50% of Hardiness.	1,234	210	1,435	In 3 turns a strong hit on everyone half through shields. Finish her sooner or raise everyone.

“Damp Cellar” cold

She likes it here. Everyone else is damp and cold.

Heroic: 1,040 to each per enemy turn, before Hardiness.
Keystone +10: 860 to each per enemy turn, before Hardiness.
Hits every fighter in the party through shields; Hardiness reduces it — better gear takes less.
The answer is healing every turn: shields do not stop cold. Healer cards do it best — they heal Health only.
No cold in normal mode.

Test strike

“Big Slap” — on boss turns 8 and 16, through shields, on whoever holds the boss’s attention (usually the tank). On heroic, while the party’s tank is alive, it goes to the tank. Not in normal mode.
Heroic: 7,000 before Hardiness; 4,200 if the target answered with a defensive card.
Keystone +10: 8,000 before Hardiness; 4,800 if the target answered with a defensive card.
One turn before the hit there is a countdown on the portrait and a warning above your hand. The target plays a defensive card on themselves: a self-shield, damage reduction or “cannot be killed”. A card someone else plays on the target does not count.

Enrage

Heroic: from party turn 40, every boss turn is 4% stronger, and it stacks.
Normal: as before — if the fight drags on past its expected length, the boss hits harder every turn.
Keystone +10: as before — if the fight drags on past its expected length, the boss hits harder every turn.

Roles

Tank

The “Big Slap” test strike lands on the boss’s 8th and 16th turn (heroic and keystone +10). One turn before, play a defensive card on yourself — a self-shield, damage reduction or “cannot be killed”: the hit becomes 40% weaker. Keep such a card in hand for those turns.
Shields do not stop this hit: the healer tops up your Health before it.
“Wet Slap” hits you. Keep Taunt on rhythm: while the boss hits the tank, the rest stay whole. The heaviest is “Wet Slap” (“Growing” phase, cycle step 1).
Do not fall: on heroic, mythic and in keystones, without a living tank the boss’s hits on its focus go through shields. A resident can be the tank too.

Healer

“Damp Cellar” cold hits everyone through shields every enemy turn: heroic — 1,040, keystone +10 — 860 to each before Hardiness. Heal everyone every turn; healer cards do it best — they heal Health only.
“Last Exhale” and “Mould in the Air” hit everyone. Before such turns, get everyone above half Health; “Last Exhale” goes half through shields: shields hold half, the rest hits Health.
“Damp Bandages” cuts healing: for those turns, shields and healing in advance.
“Mould in the Air”: damage over time — outheal it; a cleanse helps.

Damage dealers

“Dried Up”: the boss is open and takes more damage — save your strong cards for that turn.
Do not drag it out: heroic — enrage from turn 40.

The heaviest hits

“Big Slap” — test strike, through shields.
“Wet Slap” — on the tank; “Growing” phase, cycle step 1.
“Last Exhale” — on everyone, half through shields, ignores 50% of Hardiness; on entering the “Last Exhale” phase.

Loot

All of the boss’s loot with rough drop chances is in the item atlas; rules and items by boss are on the The Blighted Sanctum (East Wing — Prison of the Ancients) page.

Previous boss — Drycrown the Ancient, Sleeping Protector. Next boss — Winterfur, the Imprisoned Demon.

All bosses of the place — The Blighted Sanctum (East Wing — Prison of the Ancients). Rules of a fight against a boss with a deck — How to beat: every boss.