Hold Breath. The hydra can hold its breath for 1 hour.
Multiple Heads. The hydra has five heads. While it has more than one head, the hydra has advantage on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.
Whenever the hydra takes 25 or more damage in a single turn, one of its heads dies. If all its heads die, the hydra dies.
At the end of its turn, it grows two heads for each of its heads that died since its last turn, unless it has taken fire damage since its last turn. The hydra regains 10 hit points for each head regrown in this way.
Reactive Heads. For each head the hydra has beyond one, it gets an extra reaction that can be used only for opportunity attacks.
Wakeful. While the hydra sleeps, at least one of its heads is awake.
Actions
Multiattack. The hydra makes as many bite attacks as it has heads.
Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (1d10 + 5) piercing damage.
How many hydras for a fight?
A hydra is worth 3,900 XP. Using the 2024 encounter budgets (SRD 5.2), this is how many hydras fit each difficulty for a party of four characters of the same level. A dash means even one would be over the budget.
Party level
Low
Moderate
High
5th
—
—
1
6th
—
1
1
7th
—
1
1
8th
1
1
2
9th
1
2
2
10th
1
2
3
11th
1
2
4
12th
2
3
4
13th
2
4
5
14th
2
5
6
15th
3
5
8
16th
3
6
10
17th
4
7
12
18th
5
8
12+
19th
5
10
12+
20th
6
12+
12+
Budgets add up every monster’s XP, so you can swap some for other creatures of the same total. Try other party sizes and mixes in the encounter calculator.
How the hydra compares at CR 8
Against the 9 other challenge 8 monsters in the SRD 5.1, the hydra has more hit points than 9 of them, which makes it one of the toughest at its CR. See every CR 8 monster.
Statistic
Hydra
CR 8 average
Armor Class
15
15.6
Hit points
172
112
Best attack bonus
+8
+8
Hydra 2024 stat block
The 2024 Monster Manual revised the hydra, and the SRD 5.2 carries the new stat block. What changed:
Hold Breath. The hydra can hold its breath for 1 hour.
Multiple Heads. The hydra has five heads. Whenever the hydra takes 25 damage or more on a single turn, one of its heads dies. The hydra dies if all its heads are dead. At the end of each of its turns when it has at least one living head, the hydra grows two heads for each of its heads that died since its last turn, unless it has taken Fire damage since its last turn. The hydra regains 20 Hit Points when it grows new heads.
Reactive Heads. For each head the hydra has beyond one, it gets an extra Reaction that can be used only for Opportunity Attacks.
Actions
Multiattack. The hydra makes as many Bite attacks as it has heads.
