Right now we have only 2 types of grenades, wchich sucks in my opinion.

I think there should be more grenade types like:

Molotov, makes fire where explodes like 5-6 block radius (while in fire, you get slowness IV if someone have heatproof rune it wouldn't affect him)

Shrapnel grenade, would deal less dmg than frag grenade but would have double radius of explosion (which would be useful for tagging people etc.)

smoke grenade, Would basically make smoke 5 blocks up in radius of 6 blocks (while in smoke there would be blindness effect)

Gas grenade, this grenade would be like smoke but instead of smoke going 5 blocks it would just make smoke 5 block radius on the same y level that it exploded,
(while inside u get poison 2-4, after getting outside of it you have poison 1 for about 5-10 seconds)

If u have any other great ideas about grenades just write in comments.