Boss Challenge

Boss Challenge is the permanent practice mode for Boss Bloons. You pick any boss, Normal or Elite, put it on any map you like and play the full five-tier fight whenever you want. It pays no rewards, but it is the best place to learn a boss before its Boss Event comes around, to test a strategy on a new map or to chase personal records.

How to open Boss Challenge

You open Boss Challenge from the Events screen. It needs an internet connection. In the menu you choose a boss, a map, Normal or Elite, and whether to play casually or in Battle Mode.

All seven bosses are available: Bloonarius, Lych, Vortex, Dreadbloon, Phayze, Blastapopoulos and Diamondback. The one exception is the boss featured in the current Boss Event: while its event is live you cannot pick it here, and the menu offers a shortcut to the event instead.

Every map in the game can be used, including secret maps such as Blons and Protect the Yacht.

Rules

• Medium difficulty, Standard mode and $650 starting cash.
• Every tower and every hero is allowed.
• Rounds 1 to 39 play like a normal Medium game, with a banner counting down to the boss.
• Tier 1 spawns on round 40 at a fixed point near the entrance. Stronger tiers follow on rounds 60, 80, 100 and 120.
• The boss rounds use custom bloons: on rounds 40, 60, 80 and 100 the usual MOAB, BFB, ZOMG and BAD are swapped for groups of smaller bloons and blimps. Lych, Vortex and Dreadbloon change other rounds as well.
• While a boss is on screen, rounds start back to back, even with auto start turned off.
• You win the moment tier 5 is destroyed. There is no need to play on to round 140.
• You lose if the boss reaches the exit, if a tier survives 20 rounds after spawning, or if you run out of lives.

Normal and Elite

Every boss has an Elite version with far more health and stronger abilities. Normal and Elite results are tracked separately for every map, so beating Normal Bloonarius on a map does not count for Elite.

Casual play vs Battle Mode

Tick Battle Mode before you start to play for records. It disables Powers, Double Cash and Fast Track, and adds the same penalty timer used in ranked Boss Events, which punishes slow non-boss rounds. You pick one of three scores to display during the run:

• Fastest Time: how long the boss tiers stay on screen.
• Least Cash: how much you spend on towers, upgrades and other purchases.
• Least Tiers: how many towers and upgrades you buy.

All three are recorded after every tier, so one run can set records in each. Lower is better, but a run that reaches a higher tier always ranks above one that stopped earlier, whatever the score.

Without Battle Mode you can use Powers freely, which is handy when you only want to see a boss's abilities or test a late-game setup.

Saves and checkpoints

• Each boss has its own save slot, so you can keep one run per boss going at the same time.
• The game stores checkpoints on rounds 20, 40, 60, 80, 100 and 120. Going back to one costs Monkey Money, and later checkpoints cost more.
• After a defeat you can also retry the last round, at a higher price than a checkpoint.
• Closing the game and coming back restarts the current round for free. If a boss is on screen, play resumes as soon as the game loads.

Rewards and progress

Boss Challenge gives no Monkey Money, Trophies or Insta Monkeys, and there are no boss medals. What you get is progress tracking: a skull icon on every map where you have beaten the selected boss, blue for Normal and purple for Elite, plus your best Battle Mode scores for each map.

If you want rewards for beating bosses, play the weekly Boss Events or the team-based Boss Rush.

How to get the most out of Boss Challenge

• Practise next week's boss. Boss Events rotate in a fixed order: Bloonarius, Lych, Vortex, Dreadbloon, Phayze, Blastapopoulos, Diamondback. While one boss is in its event, the next one is free to practise here.
• Test the map, not just the boss. Event maps change every week. Try your plan on similar maps to see where farms, water towers and Paragons fit.
• Try Elite early. Elite bosses punish weak economies. A practice run shows how much income you need by each tier.
• Practise Least Cash and Least Tiers. These scoring types reward very different builds from a normal run, and Battle Mode tracks them for you.

Strategy basics

Every boss demands a lot of money, so most strategies start with heavy farming.

• Before tier 1: defend the regular rounds as cheaply as possible and put everything else into income, such as Marketplace spam, IMF Loan or Monkeyopolis. Benjamin and Geraldo add extra income. One strong tower, for example Elite Defender or The Blazing Sun, can handle tier 1.
• Tier 2: move into an Overclocked Banana Research Facility, then Banana Central or a Merchantman and Central Market setup on water maps. M.A.D, Avatar of Wrath or a spam of Overdrive, Plasma Monkey Fan Club or Destroyers can handle tier 2, especially with Embrittlement, Glue Strike, Cripple MOAB, Stronger Stimulant and Monkey Village attack speed buffs.
• Tiers 3 to 5: fill spare space with farms and plan around Paragons. Apex Plasma Master, Glaive Dominus and Crucible of Steel and Flame are realistic for tier 3, Navarch of the Seas, Nautic Siege Core, Ascended Shadow and Master Builder for tier 4, and Goliath Doomship, Magus Perfectus or Mega Massive Munitions Factory for tier 5. Normal tier 5 and Elite tier 4 often need two Paragons, and Elite tier 5 can need three or four.

Each boss also has its own counters. Read its page before a serious attempt. For full walkthroughs, see our videos on the BTD6 Master YouTube channel.

Frequently asked questions

What is Boss Challenge in BTD6?

Boss Challenge is a permanent mode where you can fight any Boss Bloon, Normal or Elite, on any map. It is meant for practice and personal records.

Do you get rewards from Boss Challenge?

No. It gives no Monkey Money, Trophies, Insta Monkeys or medals. It only tracks which bosses you have beaten on each map and your best Battle Mode scores.

Why is one boss locked in Boss Challenge?

The boss featured in the current Boss Event is locked in Boss Challenge until that event ends. Use the event button to fight it there.

Can you play Elite bosses in Boss Challenge?

Yes. Every boss has an Elite version in Boss Challenge, and Normal and Elite wins are tracked separately.

Can you use Powers in Boss Challenge?

Yes, as long as Battle Mode is off. Battle Mode disables Powers, Double Cash and Fast Track.

Does Boss Challenge work offline?

No. Boss Challenge needs an internet connection.

When was Boss Challenge added to BTD6?

Boss Challenge was added in version 40.0. All seven current bosses are included.