The Hydra is a VERY mechanically interesting monster to run! The fact that it starts with 5 heads (and therefore 5 attacks each round) is already pretty compelling, PLUS the fact that each head also packs a reaction and moving through it’s range without disengaging becomes a dangerous proposition indeed!
If you use a Hydra in your adventures (and we 100% think you should!) Make sure you hone up on the mechanics of them: for every 25 points of damage in a round they loose a head (but if they haven’t taken fire damage they regrow 2 for every head lost and get 10HP back for each head as well!) They can swim as fast as they can run so use that to your advantage!
Here’s 4 ideas for ways to drop a Hydra into your adventures:
1) “The Sleeper”: Have other adventurers, villagers, old tales talk about “The Sleeper”, a ravenous mysterious beast that lives in a subterranean lake nearby. Make The Sleeper a Hydra (mechanically they can hold their breath for 1 full hour) that lies un-moving in the murky waters of the subterranean pool. If the party doesn’t spend more than an hour poking around for it have it burst forth to claim the last member of the party that leaves the area thinking they’ve wasted a day. A 5 attack surprise round will scare even mid-tier characters!
2) Lakes and Rivers need love too! There’s plenty of big scary things in the oceans of fantasy worlds but remember there are scary things in the rivers and lakes as well. If you want a memorable river encounter look no further than the Hydra! If our memories serve us correctly we seem to recall that a rowboat RAW has 50HP and no Damage threshold. Since a standard Hydra has 5 heads that average 10 damage each hit that adds up to some serious fun: Step 1: Hydra destroys party’s rowboat, Step 2: Hydra munches on slow swimming party! Use that swim speed to your advantage (and the standard 1/2 movement for creatures without a swim speed to the party’s disadvantage)
3) Wizards should have better guard dogs: So your party is just itching to steal something from that powerful wizard? Skip boring guard dogs and surround the wizard’s tower with a moat, a moat that also has a subterranean passage that leads to the neato water-feature that dominates the entry level of said tower. Now put Fido the pet Hydra in that moat! Enjoy!
4) A bad day for fishing: Have the local fisherman hire your rag-tag band of adventurers to fix the problem with their fishery: namely something keeps eating their catches! Any guesses what’s gobbling down the fishermen’s livelihoods? Anyone? You in the front with the Critical Roll T-Shirt on… Yep you win: It’s a Hydra!