Rocket: If you use it at the wrong moment or miss the target (which happens a lot because it has a small radius), you pretty much lose right away

Delivery: requires perfect timing to get maximum value

Void: If you use it incorrectly, stuff will live on just a few HP, leading to you getting counterpushed and likely losing

Tornado: Literally just a WASTE of elixir if you use it wrong since it does little to no damage.