As a fire mage I knew I could burst him fast to get him to about 40% health but I wasn’t willing to take chances.
So you may want to do a mixture of what people suggested:
- Keep an orb on you and pull.
- Use any drums or haste increasing cooldown.
- Kill the adds ASAP and focus on bursting him down.
- Remember to have an escape (the revive titan research) because let’s be honest, the other area is a joke compared to Rexxar. Save it for him and him alone.