JuicyGrape
One thing that would be cool to create would also be the Blacklight virus from the Prototype 1 and 2 games. Another cool ability to have, and it shouldn't be too expensive, is Rou's power from re:monster to obtain the powers and abilities of the animals and objects he eats. This power causes the more he eats of the same thing, the more chance he has of gaining abilities from that thing. Also, the rarer the thing is, the better the chances of getting the abilities. An example of this is when Rou eats a sliver of the horn of a divine servant, he instantly gains a very powerful ability.