hungering cold needs a whopping 40 Runic Power. I don't think you can use it right at the start. You have to hit someone. But if you are hitting someone, he is more likely dead.

Repentance needs facing. So it basically up to the other team whether you can land it or not. Not saying not do this, but this strategy needs some work and clever tricks.

I think if they are in melee, it will be your game. But we are not countering melees here are we. We are talking wizards. So might be worth while to setup a chain (2) repentance on your kill target. This will make sure at least you can close in on him. Leave the rest 2 random (arena2,arena3). Once in melee, chain your (2) hammers, you should at least get 4 secs out of 2 stuns on him unless he goes immune. Save your DG for the 2nd target.