@Inunda
The way I got through that fight I focused on killing the spiders as they do not respawn and they're pretty vicious in the first place. Make sure you don't bunch up your units for the mushrooms to poof on ya and you can also make use of the mushroom deaths by exploding it on the enemies. The slimes are the least of your worries so basically focus on killing the mushrooms and spiders first. The rest depends on using whatever strategy you use to survive.
The moment I saw this game's thumbnail and the fact that it isn't an idle game made me a bit excited. The moment I saw the main menu screen made me feel something good.
 "You are a... The Sequel")
 "World's End Chapter 2")
 "Titan Surge")
 "MARDEK RPG: Chapter 1")
 "Hex Empire")
 "undefeated spider")
 "Swords and Souls")
 "Egg Knight")
 "Coraabia")
 "Straw Hat Samurai: Duels")
 "Dungeon Warfare"){kind=logo}
 "Pandemic 2")
 "Tap Heroes")