Early game · first 8 minutes
Take cover after Screwjab Dagger hits so she cannot keep stacking its damage and slow. Use Scrap Grenade to farm while you wait for the effect to wear off.
Rat King vs Vyper
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Mid game · Walkers
Use Royal Pestments when Vyper applies Lethal Venom. Keeping your health high reduces the damage when it triggers.
Late game · Patron
Spread out around the banner so Petrifying Bola cannot catch several teammates. Slam your banner down when Vyper closes in on a petrified teammate, giving them room to move when the effect ends.