I came up with a few champion effect ideas that would be easy and fun to implement I think.

Cinder: shoots like the arctic a small slow fly projectile but on touch it gives a burn effect to the target for a few seconds like 3 or adjustable

Thrower: picks player up and throws him p in the air. (Fall dmg , annoying)

Growing: maybe not a dmg thing but it would be fun to see a mob grow in size when hitting it (and maybe growing in base dmg a tiny bit until death)(max size to prevent overgrowth)

Maybe I will add more if I find something funny or interesting.