Addiction to this game breathes in this thread. Soon enough you will be complaining to KChamp about new weapons.
My MegaNuke is level 4 and it does 130 damage, so I would suspect MegaNuke does 140 damage at level 5.
Nuke is here in the yellow and does a level 5 damage of 112. MegaNuke is in the blue and does a level 5 damage of 140.
I'm gonna prestige up to level 3 and get the Mega nuke. I'm gonna use it if somebody steals a box from me with Tank Coins in it, then nobody will take the boxes after that.