It sounds like the bestiary entry that falls between the Crested Hydra and the Variegated Hydra. In fact it is a new imprint of Random House, soon to be part of Random Penguin. Its egregious contract terms are lovingly eviscerated by John Scalzi, Writers Beware and SFWA, with cruel but fair follow-up malleting here, here, here, and here.
As for me, what he said.
Update: more from Scalzi.
Further update: Hydra has revised their default contract offer, making the terms less egregious.