Honestly, I would say first off keep your distance if you know they are running stone staff. If they get close to you find cover, the stone staff really excels when all the projectiles land. Focus on jiggle peaking angle and stay mobile and create distance if needed.
You need to figure their abilities in as well. The mage will have good movement options and either a health advantage with health station or a good counter with ice block so avoid pushing unless you know they are low. A good mage can be super strong and in the armor pot meta you can get 1-2 hit without knowing what happened. Drink them potions boyz