Normal: Interrupt Summon Sun Orb and Inferno Leap. If you are targeted by Inferno Leap, move away even if you think the cast will get interrupted. Avoid the Solar Winds tornado. Save CDs for when Rajh goes to the center to recharge, since players get a 100% damage bonus during this time. Healer should use AE heals during the recharge phase.
Heroic: Avoid fire trail left by the Solar Winds tornado.
DPS should save cooldowns for Blessing of the Sun.
Ranged should spread out to avoid more than one being targeted by Inferno Leap at a time.
All players should watch for Solar Wind, whirlwind(s) roaming the room, and run away from it. If it hits a player, they take damage and are knocked back.
Everyone should try to interrupt Summon Sun Orb. Should one get summoned, everyone should avoid it.
Periodically, he casts Inferno Leap on a ranged. They will get a debuff, Burning Adrenaline Rush, which increases movement speed. They should use it to run out of leap's target location in time.
After about a minute, he moves to the center of the room, and casts Blessing of the Sun. Everyone should stack up, DPS should use cooldowns, and the healer should spam AOE heals.
Solar winds now leaves a trail of fire on the floor, recommend you drag boss to the far left of the room and tank there until Blessing of the Sun. Then afterwards drag him to the far right of the room and tank there. This ensures the fires are not filling the center of the room where you will be stood during Blessing. Boss should be dead before third blessing.