A.W.F.U.L. (Bloons TD Ultimate)

The Airship of Wicked Filthy Underestimated Largeness is the first known secret bloon in Bloons Tower Defense Ultimate. It is by far the strongest and slowest MOAB-class bloon, being 3x slower than a DOOM on its first appearance.

When Playing the Game
When playing the game, you must be playing in Impoppable or a harder difficulty on a map that isn't a beginner map. When these are true, round 1000 will spawn an AWFUL, instead of what the round would normally spawn for the player. However, the game does warn you before round 999 begins. It shows a pop-up that says:

''Well, well. You've made it this far? Well, you probably aren't as ready as you think. After this next round, the king of all MOABs will arrive. Nobody gets past this fight, so don't think you will. hehe, this fight is gonna be an AWFUL one...''

Despite how strong the AWFUL is, it does not spawn any children. Every time a player defeats the AWFUL, they get a random tier 5 Insta-Monkey and 1500 Monkey Money.

In Sandbox
Despite that the AWFUL only appears on round 1000 under certain circumstances, you can actually practice with it in sandbox without making it this far and here is how. Play on any difficulty and map excluding Very Easy difficulty, Easy difficulty, and Beginner maps. After completing round 500, a pop-up shows up and says:

''You've made it pretty far. Good job. We added sometime AWFUL to your sandbox, why don't you check it out?''

Trivia

 * The AWFUL was originally intended to be called the KING. This was changed due to lack of negative adjectives that start with the letter K.