Some advice, I wouldn't make changes to a card more than once every day or so. This gives you time to hear what more people think about the idea and it gives you time to consider more about what you might do with it. If it falls down the forum pages, then when you do update the card (modify post) you can always add a new comment stated what was changed and why. That will bring it back to the top of the discussion again.
As far as this card goes. I'm thinking make it a permanent, name it whatever you like, and give it a one time ability to change into a X/0 creature, X being all of your life+water Quantum (drained) divided by 5. To make this card not to OP, add wording that it cannot be used the turn that the card (permanent) comes into play. This would create at least 1 round where it is vulnerable to many things that creatures are not vulnerable to. It would then allow for pulveriser. steal (nasty!) and destroy on the Permanent side of things. And as a creature there would be time for a wall