Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Pull them in, stun them with power fist, nuke them with deathfire grasp and then use your ulti to finish them off.
Use bushes and towers and walls to your advantage, try to split up the enemy team during team fights.
An alternative build to this would be a heavy mana build with several Archangel's rods, relying on your passive to give you a nice shield absorb if you get low health.