Round 4 (BTD6)

Round 4 is an early-game round appearing in Bloons TD 6. It is the second round with Blue Bloons, and a notorious early-game round due to how dense the group of Blues are at such an early stage of the game.

Description
Round 4 is characterised by a seemingly normal stream of Red Bloons, before a tightly packed swarm of 18 Blue Bloons rushes in, with a few Red Bloons bringing up the rear.

Strategy
It is very difficult of a round when compared to how early the round appears. Given that a normal game of Impoppable and CHIMPS skip this round entirely, a standard game may require a few bloons to be leaked in order to survive. Use of Mana Shield and/or Pre-Game Prep is very recommended.

Tips

 * 0-0-0 Alchemist is the single best option for handling Round 4. However, this will be harder to pull off on multi-lane maps, simultaneous or not, and even alternating lanes can cause trouble for Alchemist.
 * Boomerang Monkey can beat this round with only a small amount of trouble, and almost none if given Improved Rangs.
 * Sauda can single-handedly deal with this round given the map is single-lane and Sauda has enough track coverage.

Trivia

 * Coincidentally, a BTD1 Pre-Round Comment for beating its respective Round 4 makes a comment alluding that future games could not be beaten with just Dart Monkeys. BTD6 Round 4 is really difficult to beat with just Dart Monkeys, even if a Dart Monkey is upgraded to any Tier 3 upgrade.