Some tips for the bosses (POSSIBLE SPOILERS)
Wave 20 Boss (The Mage) : Don't shoot his shield or you are just going to waste ammo, shoot his magic orbs to make him vulnerable, i recommend to you to use the Tec-9 or the SMG.
Wave 40 Boss (The Tank): Probably the easiest boss in the game, just use some grenades and when the little bunny is outside shoot him to death. (You can use any good powerful weapon)
Wave 60 Boss (The Queen Bunny): I highly recommend you to have the Full Upgraded Minigun (try to not overheat the gun and have atleast 500 bullets as ammo), you can use some grenades for extra damage.
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