He is a hero that needs a lots of mana for his spells, always aim for golem buff cose he need CD as well.At the start farm alot in the midd lane dont focus hero until u get a chance to kill him, always aim for creeps.Use ur spell combo wisely. U have 2 ways of using them.
1) Go for CONFLAGIRATION, afther that use fast SEAR, then PILAR OF FLAME, and if u needed use ulty...This is for 1v1 fight.
2) For massfight use PILAR OF FLAME 1st, afther that use CONFLAGIRATION and PYROCLASM wery fast to make as much DMG as posible. And leave SEAR for guys who try to escape to stun them.
In TF(Team fight) do not by any chance encounter enemies at the start or 1st, always come from bushies and stuff an always come from around to mass ur spells and make as much DMG as posible.Anyhow ull get ur kills wery easly.