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.
This is my how-to-play pantheon as a DpS (Damage per Second) guide.
First skill have to be the second skill named Aegis of Zeonia, because of the stun, it makes it way easier to take down a first kill.
When you reach level 2, then you take the skill Heartseeker Strike, because then you can stun with Aegis, and then fast use the Heartseeker strike for a lot of damage.
Every time you can raise Heartseeker strike, do it.