Beast Heart Adept and other monstrous companions

[yougi]

So one of my players has asked me if I would let him, if he took levels of BHA (Dungeonscape p.48), to take companions outside of the given list. I told him it would be possible, but I'd have to judge each of his ideas first. I also told him that while CR was a good starting point, creatures with SLAs could be overpowered, and same with flying creatures which could be mounted.

His first proposition was a Hydra. I told him he could have a 6 headed Hydra at 3rd level, and an 8 headed Hydra at 5th. My logic was that these Hydras have the same CR as, respectively, Manticore and Chimera, and I thought that the advantage for a PC to have a flying companion was pretty similar to the Hydra's "resistance".

So two questions: (1) do you think my decision was appropriate? (2) What is it like to play/DM a Best Heart Adept, if you have any experience?

[Flickerdart]

Hydras are way under-CRed when played intelligently, and are in no way appropriate anywhere near the hands of players.

[Kuulvheysoon]

Hydras are way under-CRed when played intelligently, and are in no way appropriate anywhere near the hands of players.

Good Gods second'd. Hydras can be downright nasty.

[Akal Saris]

Clever player - hydra's a good pick for a strong monster without flight or SLA's. Lots of dice rolling though.

I think it would be fine for a game with experienced players. I had a PC with a hydra companion (8 headed at PC level 10), and the hydra's biggest challenge was its terrible to-hit score. Yes, she could take a lot of damage without dying, but she was basically a big scaly wall most of the time.

If you do allow a hydra, I'd recommend making the hydra take the Dungeonbred template (Dungeonscape 112). Reducing its size from huge to large will make it easier for the PC to take it into dungeons, and reducing its threatened range makes the hydra's attacks of opportunity less of an issue.