Early game · first 8 minutes
Use Sand Blast to stop Rat King’s gunfire while your lane partner shoots him. Use Scorn when he is close to the wave so you can damage him and the troopers while healing.
Mo & Krill vs Rat King
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Mid game · Walkers
Approach Rat King from the side with Burrow. Use Combo after Royal Pestments ends, with teammates close enough to shoot him while you hold him.
Late game · Patron
After Rat King slams his banner down, use Sand Blast on his nearby teammates, then hold him with Combo while your allies attack.