Ability Concept: Self Destruct

I know most people here have played pokemon, and sometimes tactically exploding a pokemon if it is low health, or may take a strong enemy with it is a good decision.

A champion having this ability could have interesting gameplay and I'd love to see it happen. I also have an idea for a basic design...

First off, the self destruct probably should not be a basic ability. It needs to be an ultimate. Secondly, it can't have absurd damage or too high of a radius (otherwise it would become a bomber that continuously destroys entire enemy teams and that isn't fun for anybody). Thirdly, giving someone a basic SUICIDE isn't the direction I feel League should be going, there needs to be some hope of something additionally... Lastly, this champion with the ability to cause self destruction needs to do it in a relatively sane way. (What character for any reason would fight on the Rift with the sole intention of dying)?

So I imagined something like a method of flight. Straight up. The character selects a landing position and shortly after, they begin accelerating straight down. There could be a timer with the most damage tied to the longest delay (higher you go up, longer it takes, more damage). When this champion lands, if they hit another champion, even without causing death to them, the other champion would probably break most of their fall...

They could survive (possibly take some damage) and this ability goes on cooldown. If this ability misses, they are launching themselves straight toward the ground.... They die. The last enemy champion to attack gets full credit for a kill and enemies get assists.

If a low health champion begins this ability and hasn't recently been attacked, even if they miss the ability and die, no enemy will receive gold for the kill.

Edit: I'm also imagining that the ability could be less of a direct suicide and just use x (health %) of the champion's health if they hit the ground instead of a champion. (In this case, the damage would be reduced or delay increased...)