Aeonglass is the Act 3 Glory boss with 512 HP and a fixed three-move cycle. She also starts with 3 Artifact, which means your first three debuff applications do nothing. Those two facts decide the whole fight: you can pre-block every turn because nothing is random, and you cannot open with a Weak or Poison plan because the Artifact eats it.
The pool is the largest in the game — 512 against the Queen’s 400 and the Knowledge Demon’s 379. On Ascension it becomes 535, the single biggest HP increase any boss gets (+23).
The fight at a glance
| Act | Act 3 — Glory |
| Type | Boss |
| HP | 512 (535 on Ascension 10) |
| Starting power | 3 Artifact |
| Pattern | Fixed: Ebb → Eye Lasers → Increasing Intensity |
| Damage per cycle | 48 (56 on Ascension) |
| Block she gains | 33 on the Ebb turn |
Every move, with numbers
| Move | Intent | Damage | Ascension | Other effect |
|---|---|---|---|---|
| Ebb | Attack + Defend | 26 | 32 | Gains 33 Block |
| Eye Lasers | Attack | 11 × 2 = 22 | 12 × 2 = 24 | None |
| Increasing Intensity | Status + Buff | 0 | 0 | Adds a Status card and buffs herself |
Only two of the three moves deal damage. That is the opening: one turn in three is free damage on her side but also free setup on yours — no block required, so it is the turn to play powers, draw engines and scaling.
The cached move record lists Increasing Intensity’s intent as “Status + Buff” but carries no power payload, so treat the escalation as real but unquantified: the fight gets worse the longer it runs, and the data does not tell you by how much.
The cycle maths
One full cycle is Ebb (26) + Eye Lasers (22) + Intensity (0) = 48 damage over three turns, or 56 at Ascension (32 + 24). That is 16 damage per turn averaged out, which is a low clock for a 512 HP boss. The pressure is not the average — it is the two spikes landing on known turns.
Because the order never changes, you can plan two turns ahead:
- Turn 1 — Ebb. The 26 (32) hit plus 33 Block on her side. Your block has to cover 32 at Ascension, and your damage this turn is mostly eaten by her Block.
- Turn 2 — Eye Lasers. 22 (24) in two hits. No Block on her side, so this is the turn your damage actually lands. Multi-hit means per-hit Block (Dexterity, Thorns) is efficient.
- Turn 3 — Increasing Intensity. Zero damage. Play your powers, your card draw, your setup. Nothing to block.
Then it repeats. There is no shuffle and no branch, so a failed turn 1 is recoverable: you know exactly what turn 4 looks like.
“Pattern: Ebb → Eye Lasers → Increasing Intensity → repeat. Innate: 3 Artifact.” — STS2 boss data, slaythespire.wiki.gg
How much damage you need
512 HP across a fight that averages 16 incoming damage per turn means the real constraint is your damage per turn, not your block.
| Turns to kill | Damage per turn needed (512 HP) | Damage per turn at 535 HP |
|---|---|---|
| 6 | 85.4 | 89.2 |
| 8 | 64.0 | 66.9 |
| 10 | 51.2 | 53.5 |
| 12 | 42.7 | 44.6 |
Six turns is aggressive for most decks and means killing her across two full cycles. Eight turns is the realistic target — 64 damage per turn — and it fits inside the “end it before Increasing Intensity stacks too far” rule.
For scale, real card numbers: Hyperbeam deals 28 to all enemies for 2 energy (36 upgraded), Bury deals 52 for 4, Bludgeon 32 for 3, and Grand Finale 60 for 0 if your draw pile is empty. Two Hyperbeams plus a Bludgeon is 88 in one turn — enough to close a 512 pool in six turns if the rest of the deck contributes.
Blocking the two spike turns
The block requirements are simple because there are only two.
| Turn | Damage to block | Card that covers it | Cost |
|---|---|---|---|
| Ebb (Ascension) | 32 | Impervious+ (40 Block) | 2 |
| Ebb (normal) | 26 | Impervious (30 Block) | 2 |
| Eye Lasers (Ascension) | 24 | Panic Button (30 Block) | 0 |
| Eye Lasers (normal) | 22 | Fight Through (13) + any 9 | 1 |
Impervious at 30 Block for 2 energy covers the normal Ebb with 4 to spare and the Ascension Ebb only when upgraded to 40. Panic Button’s 30 Block for 0 energy is the cleanest answer to Eye Lasers, though its “no Block from cards for 2 turns” clause means you cannot use it the turn before an Ebb.
The Artifact problem
Three Artifact stacks absorb the first three debuffs you apply — and they absorb them whether you meant to apply them or not.
- Do not open with Weak or Vulnerable. A 3-stack Vulnerable Potion is fully consumed by the Artifact and does nothing.
- Do not open with Poison. Three Poison applications vanish before any tick matters.
- Do open with Strength or Dexterity. Buffs on yourself are not debuffs and are not absorbed.
- If you must strip it, strip it cheaply. Three 0-cost debuff cards remove the wall, and then your real debuff lands on turn 4.
This is the single biggest mistake in the fight: a deck built on Vulnerable uptime spends its first three applications on nothing, then has to rebuild the stack while she is already at 33 Block on Ebb turns.
Turn-by-turn plan
| Turn | Her move | What you do |
|---|---|---|
| 1 | Ebb (26/32, +33 Block) | Block the hit. Do not waste a big attack into 33 Block. |
| 2 | Eye Lasers (22/24) | Small block, maximum damage. This is the race window. |
| 3 | Increasing Intensity (0) | No block. Play powers, draw, scaling. |
| 4 | Ebb again | You know it is coming — hold block in hand from turn 3. |
| 5 | Eye Lasers | Second race window. |
| 6 | Increasing Intensity | Second free setup turn. |
| 7+ | Repeat | If you are here, you need 64+ damage per turn to finish. |
The hand-holding trick is on turn 3: because turn 4 is a known 32-damage hit, any block card you draw on the free turn should be held (Retain) rather than played. Cards with Retain — 11 in the card file — make this trivial.
What to bring
- Big single-target attacks. 512 HP rewards raw numbers over multi-target: Bury (52), Bludgeon (32), Break (20 plus 5 Vulnerable, once the Artifact is gone).
- Retain or Block banking. Turn 3 is free, so banking 32 Block into turn 4 converts a dead turn into a defended one.
- Dexterity, not Weak. Weak is absorbed by Artifact; Dexterity improves every Eye Lasers hit you block for the rest of the fight.
- One cheap debuff stripper. Three applications is a real cost if each one is a good card.
Where to go next
The boss table ranks every boss by HP and biggest hit, and the monster index covers the other 114 entries. For the damage side, the cards database lists every attack with its cost and upgrade, and the Ascension page shows how far each boss moves. If you are still building the deck, start with deckbuilding basics.