So I had been thinking about a new summoner spell, which I called Hand of Death (imagine icon of a hand that looks like you're going to die in a second). You instantly kill target enemy champion. No cooldown, but one time per game usage.
This way, it's a very strong spell, but you have to use it well. If you just use it to make a random kill that is not important, it is in fact wasted. However, if you can kill the enemy AD carry in an endgame teamfight with it, you can proceed to make an ace and then take down a turret, an inhibitor, and another turret.
What do you think about it?
EDIT: I'd like to add 2 things:
1. Please give reasons why you don't like it.
2. It seems that, for some people, it isn't clear what the range is. I thought around equal to Ignite and Exhaust.