Guide to 5th slot

To get 4th slot You need to beat the game (38 rounds) without losing a single heart on either hard or normal to unlock 4th slot. Easiest way is to get carried by some decent people in duo trio or quad.

To get 5th slot, you need to beat the game on quad. You must have the most kills out of everyone, and you must have at least 300 kills. The other players also cannot leave. Losing hearts is ok as long as you don't lose.

Towers required: mortar, goldmine, farm, rocket battery.

before round 1: try to place down 4 goldmines before round start
round1: place down mortar and 2 more gold mines
round2: upgrade mortar and place down 2 more gold mines
round3-6: upgrade your gold mines one at a time. if you cannot afford the upgrade, try to spend all gold on lower level upgrades of other gold mines.
round 7: deploy rocket in the back
after round 7:max your 8 gold mines.
after maxing gold mines: max your 1 rocket. sell mortar for farm. Farm will grant you more slots (up to +5 slots at max level) to place down more rockets. Make sure to max your rocket before placing the next one. after you max your farm and max all your rockets, sell gold mine 1 by 1 and buy rockets, once again maxing them each before selling the next farm.

You should have 14 rockets and 1 farm. set 5 to weakest, 5 to first, and 4 to last to maximize kills.

Your teammates should have paladins, berserker and optionally, grove warden to support. their rockets should be set to strongest to help damage but not steal kills.

NOTE: Rockets should go in the back so their deadzone does not limit them from firing. Goldmines should go in the front to avoid taking up space from the rockets.