I'm with Jmizzle on this one. Empathic bond on a creature would simply me too game breaking, as would immortalize. How do you counter an Armajio (sp?) with Empathic Bond? You simply couldn't, save for reverse timing it or mutating it (adding even MORE incentive to use druids). What about a 14/6 dragon with deja vu? You could 2x fire storm it, devour it, lobotomize it and then sundial, ignore it because you have a 100 strength bone wall, mutate it, reverse time it, etc.
A 14/6 dragons are not gamebreaking. Miracle regularly gets 24/24 light dragons on me, and they aren't that hard to deal with. Just reverse time it or mutate it then devour. Heck, I've even 2x fire bolted it and then ate it :s.
What about a bone dragon with immortalize? You would only have one turn to counter it, unlikely, before you're screwed.
With empathic bond, there's a reason it's only a spell. Getting even two empathic mutations would be game breaking, as since that assumes you have a fallen druid it is much harder to kill them. With empathic bonds as a spell, they can be stolen, destroyed, etc. With them as a creature, the only viable option would be to fire bolt it, as most mutants have higher than 3, or even 6 health for 1-2 fire storms. Devouring wouldn't be an option as if you have a fallen druid you're most likely mutating any otugh that the opponent gets to prevent the druid from being eaten. The only other solution besides fire bolt/ice bolt/drain life would be eagle eye, but the eagle eye would never get in that situation as your druid would be killed.
Overall, having all card spells as permanents would be entirely broken. Graveyard, hasten, blessing, empathic bond, earthquake, gravity pull, etc. would all be horribly OP with them as creatures.
