Guardians

Every biome is held by a Guardian — a milestone expedition boss. Beating a biome's Guardian is what unlocks the next biome, so the Guardian chain is the backbone of progression. This page covers each Guardian's stats, exactly how the fight is decided, roughly how much gear it takes to win, and everything you can stack to tip the odds.

The Guardians

A Guardian unlocks once you've cleared its biome's patrols and reached the listed Expeditions level. Difficulty is the single number the fight is rolled against (see below). Since v0.36.12 every Guardian unlocks strictly below the next biome's patrol, so the ladder always reads forward.

#	Biome	Guardian	Expeditions level	Difficulty
1	Grasslands	Thunderfoot Matriarch	5	60
2	Redwood Wilds	Old Growth Tyrant	20	150
3	Murkwater Swamp	Murk Sovereign	27	200
4	Cavern Depths	Hollow King	35	240
5	Scorched Badlands	Scorched King	41	260
6	Coral Shallows	Tide Leviathan	44	290
7	Frozen Wastes	Frostmaw	50	320
8	Ashen Peaks	Ash Tyrant	55	380
9	Skyreach Plateau	Sky Sovereign	58	420
10	the Sundered Vale	The Sundered One	65	500

Beat The Sundered One and the Rifts tear open — three endgame zones with their own repeatable bosses (see Rifts and the Endgame Guide).

How the fight is decided

A Guardian fight (like any expedition) is a single automatic roll of your expedition score against the Guardian's difficulty. It plays out on the Trail as a four-stage encounter, but the outcome is decided by one clean formula:

Win chance = score ÷ (score + difficulty)

So your win chance depends only on the ratio of your score to the difficulty:

Score ÷ difficulty	Win chance
×1 (score = difficulty)	50%
×1.5	60%
×2	~67%
×3	75%
×4	80%
×6	~86%
×9	90%

There's no hard gate — you can attempt a Guardian at 30% and get lucky — but each attempt costs health (below), so it pays to build score first.

What "score" is made of

Your expedition score is one pile, assembled from:

score = (attack × 1.5) + defense + party + bonuses

Attack — your equipped weapon and trinket attack, any forged attack, and attack potions. Attack is worth 1.5× in the formula, so a stronger weapon is the single most efficient upgrade.
Defense — your armour, shield and trinket defense, forged defense, and defense potions.
Party — each uninjured companion in your expedition party adds power + (guard + swiftness) ÷ 2. A strong, bred and imprinted party is a huge share of your score.
Bonuses — a flat pile added on top: the full-set bonus of a worn expedition set, the Watchtower, Museum wing perks, Mastery expedition perks (these scale with the Guardian's difficulty), War Banners (+1 each), the Rift Standard (+10), Weather, Pets, and dino trinkets (a Vale Charm adds +5 each).

The game shows your exact win chance on the Guardian's card before you commit — and because the displayed number uses this identical pile, the card never lies.

How much gear it takes

Turn the formula around: to reach a target win chance against a Guardian, you need score = difficulty × (target ÷ (1 − target)). In practice:

Coin-flip (50%) — score equal to the difficulty.
Comfortable (~67%) — score double the difficulty.
Safe (80%) — score four times the difficulty.

Guardian	Difficulty	Score for ~67%	Score for 80%
Thunderfoot Matriarch	60	120	240
Old Growth Tyrant	150	300	600
Murk Sovereign	200	400	800
Hollow King	240	480	960
Scorched King	260	520	1,040
Tide Leviathan	290	580	1,160
Frostmaw	320	640	1,280
Ash Tyrant	380	760	1,520
Sky Sovereign	420	840	1,680
The Sundered One	500	1,000	2,000

Gear rule of thumb: each biome's own expedition set is tuned to roughly match its Guardian — so equipping the set for the biome you're clearing (worn for its full-set bonus, backed by a decent party) lands you in the comfortable band. A full Sundered set plus a strong party, for instance, clears The Sundered One. When you're short, the fastest gains are a better weapon (×1.5 in the formula) and a few set pieces farmed off the Guardian's own patrol.

Taking damage and staying alive

Every run costs health — even a win. Damage is drawn from the difficulty:

On a win: about 40% of the difficulty in HP (a spread of roughly 24–56%).
On a loss: about 80% of the difficulty (roughly 48–112%).

So a win against The Sundered One (difficulty 500) costs ~200 HP; a loss can cost ~400+. That makes max HP and a stock of cooked food as important as score for the late Guardians. Ways to soften it:

House chain (Thatch Hut → Iron Keep) raises your max HP.
Guard party role — each Guard cuts damage taken by 15%, down to a −30% floor with two or more (v0.36.64). Guards now also protect you on hunts and rival duels, not just expeditions.
Keep food in the Bank; auto-eat heals you mid-fight.

Death: if a blow would drop you to 0 HP while you are actively playing and auto-eat has no food left, you die — losing that run's spoils and one equipped item where you fell (reclaimable; see Death and reclaiming gear). Offline, a run always stops safely before a knockout, so you can never die away from the keyboard.

Guardian Heat

Re-fighting a Guardian heats its biome: each Guardian win adds a heat stack worth +8% difficulty, up to 10 stacks — so a farmed Guardian gets steadily harder (this raises the effective difficulty the formula uses). Heat cools one stack every 2 hours, and each patrol win in that biome vents a stack. For a first clear this rarely matters; when farming a Guardian for its set, interleave patrols to keep the difficulty down. See Guardian Heat.

Fleeing

If a run is going badly you can flee rather than fight to the end. Flee chance rises with your party's total swiftness, and each Scout adds +10% flee chance (and +4% Trail Cache finds). Fleeing avoids the worst of a loss's damage.

Beating the next Guardian — checklist

Equip your best gear — the strongest weapon (×1.5 in the formula), armour, shield, and trinket you can craft, forge, or find.
Wear the biome's expedition set — farm a few pieces off the Guardian's patrol for the per-piece stats and the full-set bonus.
Bring your best party — bred/imprinted high-power companions, with roles: Attack for score (×1.2 power each), Guard to survive (−15% damage each, −30% floor), Scout to flee (+10% flee chance each).
Stack the flat bonuses — Watchtower, Museum wings, Mastery expedition perks, War Banners, the Rift Standard, and a favourable sky.
Bring HP and food — build the house chain and stock cooked food; even a win hurts.
Check the card — it shows your exact win chance. Aim for the comfortable band (score ≈ 2× difficulty) before committing.