This is common sense (IMO) but I've seen at lot of mages fail at the Archimonde encounter due to the knockback anc the fires that spawn.
Ezmode knockback:
While you should have a tear in your inventory to slow your fall when Archimonde knocks you back you don't have to use it as a mage. There is actually a better, quicker way of fighting the knockback.
What you do is when you are the air after the knock back, aim the camera towards the ground and blink. You wil instantly blink to the ground while the rest of your group slowfalls down using their tears. This allows you to get back to decursing and DPSing quicker.
Also, as a mage, one of the key classes in the Archimonde encounter, you should have both a PVP-trinket and your Iceblock ready. The fires that spawn on the ground are fatal, and both the PVP-trinket and Iceblock will break the fear Archimonde casts that can cause you to run into the fire (Iceblock also makes yo uimmune to the dmg dome by the fires).
As I said, common sense, but if someone haven't thought of this before and is helped by the advice