Okay, I was playtesting the Hydra a bit. I'm considering rewriting the Regneration power to this:
Hydra’s Regeneration: [-8]
Musts: You must attach a Catch to this power. High concept must relate to being a Hydra.
Description: Whenever you lose your head, you grow two more.
I Got Better: Whenever you take a consequence and lose your head, you may tag the consequence for free to grow two new heads at the beginning of your next turn as a supplemental action.
It’s Just a Flesh Wound: You may take an additional Mild Consequence for each head you regrow with this power. Each consequence you take results in losing one of your heads.
Stacked Catch: As Physical Immunity.
I've also found that I like this better for the extra heads (thanks Sanctaphrax):
Extra Appendages [-2]:
Requirements: Appropriate High Concept.
Skills Affected: Fists, Weapons, Guns
Effects:
Multiple Targets. You may make spray attacks with anything, within reason.
Mix And Match. You may use multiple different weapons in a single spray attack. Use the lowest applicable skill. You may also make attack-like maneuvers as part of a spray attack.
Excellent Coordination [-1]. For each purchase of this power, add 1 to the accuracy of each attack or maneuver within spray attacks that you make. This cannot increase accuracy beyond the number of shifts that you had to split up between attacks in the first place.
Coordinated Attack [-1] When attacking a single target, you may add 1 to the accuracy of an attack or maneuver directed at that target.
This almost exactly what Scant wrote up, but I removed the recovery trappings (and created the separate power). I also added Coordinated Attack for benefit against a single target.
And to model the other benefits of multiple heads:
Multiple Heads: [-3]
Description: You have more heads than normal.
Musts: You must have a high concept relating to having multiple heads.
Skills Affected: Alertness, Scholarship, Investigation
Many Eyes and Ears: You gain a +2 bonus when using the Avoiding Surprise and Passive Awareness trappings of the Alertness Skill. You also gain +1 to all Investigation rolls involving the Eavesdropping, Examination, and Surveillance trappings.
Two Heads are Better than One: Gain +1 on all rolls with the Scholarship skill.
This is basically a bundle of Stunts.