Upper path is mostly unchanged. 3rd Upgrade adds +1 Layer Buster and +1 Pierce, also makes shots Powered, so it pops Ice and Metal. Middle path gives power, Lower path, efficience. In example, a -/2/1 shot may hit 12 Bloons and a blue, while a -/2/0 may hit 25 Bloons, but just for 2 layers popped. Cripple MOAB deals +2 Damage to MOABs, and just Cripples 1st MOAB hit.