A more situational ignite.
So instead of ignite doing fixed amount of damage, make it so that it does increased amount of damage the more missing health the enemy has. In short , make it work like an execute so that it does less damage when used on full hp targets than for example someone with only 50% of health remaining.
It adds more strategy to free targeted damage, and also makes it situational which should act as a nerf to ignite. This idea has already been mentioned before so i am just bringing it up again for awareness as i genuinely think it will be a good start in nerfing ignite so that other summoners are brought into play whilst ignite isn't completely out of play.
Last but not least, i don't know if this change has been made into the recent patch, but please remove ignite procing one stack of electrocute. It just means that some champs like Zed, can ult, ignite and AA and blink back to safety whilst procing electrocute at the same time. Not a Zed hate thread but just pointing out how easy it is to proc ignite by someone who has enough mobility to catch up to you and then run back to safety, without giving you a window of counterplay.