How to beat wave 9 in Balloon Tower Defense
You had a comfortable board through wave 8. Then four silver balloons came down the path, your darts pinged off them, and you lost most of your lives in about ten seconds. Those are Mylar Balloons, wave 9 is the first wall in the game, and it is meant to be — a run that never fails once has no reason to press Retry. Here is exactly what changed and the cheapest way through.
What actually happens on wave 9
Wave 9 on Meadow Run is two groups. First, four Mylar Balloons, spawned about 1.6 seconds apart. Two seconds after the first Mylar, twelve Foil Balloons start arriving roughly every 0.7 seconds. Foil moves at almost twice the speed of Mylar, so the two groups overlap and the fast foil catches up and mixes in with the slow silver ones.
That overlap is the trap. The Mylar needs a damage type your board probably does not have yet, and while you are busy not killing it, twelve fast Foil Balloons are also going past. Clearing the wave pays a 112-coin bonus, and wave 10 opens with a Zeppelin, so you cannot afford to limp out of this one broke.
Why your darts stopped working
Every Mylar Balloon has a reflective film, and in game terms that film is a damage multiplier. This is the whole of it:
| Damage type | Towers | vs Mylar |
|---|---|---|
| Blunt | Dart Post, Tack Ring | ×0.5 — half damage |
| Shock | Static Coil | ×0.6 — also reduced |
| Pierce | Pin Cannon | ×1 — full damage |
| Burn | Sun Lens | ×1 — full damage |
A Mylar Balloon has 8 health. A level-2 Dart Post throws for 1 damage at 2.2 shots per second, which the film cuts to 0.5 — so a single Dart Post needs more than seven seconds of unbroken fire to pop one Mylar, and there are four of them plus twelve Foil. That is why the wave feels like your towers switched off. They did, by half.
The fix: add pierce or burn — do not replace your board
Two towers ignore the film completely: the Pin Cannon (pierce) and the Sun Lens (burn). You only need one of them, and the key word is add. Your existing darts and tacks are what kill the twelve Foil Balloons; if you sell them to afford the counter, you trade one problem for a worse one.
Pin Cannon — the answer you can prepare
The Pin Cannon unlocks on wave 5, costs 350, and its pins do full damage to Mylar. It fires slowly — about one shot every 1.8 seconds — but each shot does 6 and passes through two balloons, so two shots kill a Mylar and clip whatever is behind it. It targets the strongest balloon in range, which on wave 9 is always a Mylar, so it sorts its own priorities. One Pin Cannon on a good spot handles all four.
Sun Lens — only if you have spare money
The Sun Lens unlocks on wave 9, so you cannot build it during the wave-8 build phase — you would be placing it mid-wave while balloons leak. It costs 400, burns through the film, and its burn stacks keep ticking after the beam moves on, which is good against a line of Mylar. Take it only if you are cash-rich and already have foil coverage. Otherwise the Pin Cannon is the cleaner call because you can have it built and aimed before the wave starts.
The build, step by step
During wave 8, bank coins
Wave 8's own hint is "bank coins, something armoured is coming" — that is this. Do not upgrade anything speculative during wave 8. You want at least 350 spare by the time it clears. Between pop rewards and the wave bonuses, a board that was not overbuilt will be comfortably above that.
Place the Pin Cannon on a long sightline
Because it fires so slowly, the Pin Cannon wastes its window on a corner. Put it where it can see a long stretch of path at once — on Meadow Run, the long middle section or the final straight before the exit. It has a 150-range circle at level 1; line that circle up along the path, not across it.
Leave your dart line alone
Keep every blunt tower you already have. Their job on wave 9 is the twelve Foil Balloons, which have only 2 health each and take full damage from darts. The Pin Cannon does the silver ones; the darts do the blue ones; between them the wave clears.
If it is still close, upgrade the Pin Cannon once
Level 2 costs another 350 and takes the pin to 9 damage and 3 pierce — a one-shot on Mylar and a longer line through the balloons behind it. Worth it before you spend on anything else, and it carries straight into wave 10.
Five mistakes that lose wave 9
- Selling darts to afford the counter. Now nothing kills the twelve Foil Balloons, and you lose the wave to the group you could handle.
- Upgrading Dart Posts to level 3 to brute-force through. Triple shot for 2 each is still halved to 3 per volley against Mylar, and you just spent 250 that should have been the Pin Cannon.
- Putting the Pin Cannon on a corner. Its slow fire rate needs a long sightline. On a bend it gets one or two shots off and the Mylar walks on.
- Buying the Sun Lens mid-wave. It unlocks on wave 9, so building it now means placing it while balloons are already leaking. Prepare the Pin Cannon during wave 8 instead.
- Spending your last coin. Wave 10 is a Zeppelin with 250 health. Come out of wave 9 with something in the bank.
After wave 9: the Zeppelin on wave 10
Wave 10 opens with a single Zeppelin — 250 health, resistant to blunt and shock, worth 150 coins when it pops — followed by a stream of twenty rubber balloons five seconds later. Your upgraded Pin Cannon is already most of the answer, because pierce is one of the few things the Zeppelin does not resist. Keep it aimed at the long straight and let the darts mop up the rubber behind it. The full breakdown, including why the Frost Fan is the Zeppelin's hardest counter, is in how to beat the Zeppelin.
Quick recap
- Wave 9 = 4 Mylar (halve blunt and shock) + 12 fast Foil, overlapping.
- Add one Pin Cannon (350, pierce, ignores the film). Build it during wave 8.
- Put it along a long straight, not on a corner.
- Keep your dart line for the Foil. Do not sell anything.
- Leave coins for the wave-10 Zeppelin.