Bonus (Enemy)

The Bonus enemy is a very rare enemy that can be found (theoretically) on any level. Instead of spawning a wave of these enemies, this enemy just spawns with some other enemies at the start of a wave. It does not incur a life penalty if it reaches the Base.

Appearance
It is a yellow five-pointed star with a lighter yellow outline.

Strategy
These enemies are blessings and curses.

When killed, the Bonus enemy will drop: Coins/Green Paper proportional to your wave, 50 lives, or a free (randomly chosen) global upgrade! If you do not manage to kill it, it will not harm your base.

However, it has an annoying tendency to draw fire away from other enemies, especially if your towers are set to target First. It takes 98% reduced damage from every single tower in the game, making it harder to deal with than Light enemies with tons of health. However, it does have a weak point. Depending on what your 5 least used towers will be in-game, one will be randomly chosen, and that tower's icon will appear over the bonus enemy. If that tower shoots the Bonus, it will do extreme damage to it, bringing it down in a matter of seconds (time varies on the tower). (The Bonus enemy cannot choose Air or Freezing towers, since they cannot attack it in any way or form.) One can still bring down the Bonus without the specified tower, but it will require a lot of high-damage towers. If you can kill it, the reward is definitely worth it.

Trivia

 * This enemy was removed from the second game and replaced with 5 new bosses; however, the icon from this enemy is still used for boss enemies.