I think hindsight would be a rockin spell.. not for a creature though.. im thinking instant... maybe returning a permanent to owners hand that's been in play for at least one turn... but heavily reduce the cost..
like:
Hindsight UU instant
Return up to 2 permanents target player controls to their owner's hands. You may only target permanents that have been in play for at least 2 turns.
maybe with a pic of a guy looking behind his shoulder.. or thinking

hmmmm....
regarding gang warfare... i thought about basically making it a wrath of god... for black... and simplifing it.. so ppl go... OH COOL.. not WTF????
I'm thinking instead of all the crazy text...it might read
Each player chooses a creature they control with the highest converted mana cost and an opponent. The chosen creature deals damage equal to it's power to all creatures the chosen opponent controls. All damage is dealt simultaneously and cannot be prevented. Creatures can't regenerate this turn.
simpler... does pretty much the same thing... and sometimes more...
each player has a fatty... and sacs the rest... basically...