For Challenge # 064. I was trying to think of powerful, simple effects that can't exist in a single colour, which is what a four-colour card ideally needs to be made of. I was thinking of going for the charm approach, combining three two-colour effects, but then Vindicate leapt to mind. It's pretty much the poster effect for "powerful, simple, and nonmonocoloured".
Vindicate can exist as a sorcery for or (Maelstrom Pulse). So as a 4-mana effect it had better be instant. What to add for the fourth colour? Blue and red could both offer fairly natural options, but "damage equal to CMC" is such a natural Red kicker effect (Agonizing Demise, Orim's Thunder, etc) that I went with that.
For Challenge # 064. I was trying to think of powerful, simple effects that can't exist in a single colour, which is what a four-colour card ideally needs to be made of. I was thinking of going for the charm approach, combining three two-colour effects, but then Vindicate leapt to mind. It's pretty much the poster effect for "powerful, simple, and nonmonocoloured".
Vindicate can exist as a sorcery for
or 
(Maelstrom Pulse). So as a 4-mana effect it had better be instant. What to add for the fourth colour? Blue and red could both offer fairly natural options, but "damage equal to CMC" is such a natural Red kicker effect (Agonizing Demise, Orim's Thunder, etc) that I went with that.
I love this. Good job. Blue is the only color that doesn't get "destroy" effects outside of Polymorph-style cards.