Phantom Assassin is a melee character. Her primary attribute is agility. The hero is mainly taken to the easy lane as a carry. Most effective in the mid and late game.
Stifling Dagger allows Phantom Assassin to farm gold in the lane while being at a long distance from creeps. With Phantom Strike, the hero quickly shortens the distance with the enemy, which makes her especially effective against ranged opponents. Blur allows her to move around the map more safely. The ability also forces opponents to buy the Monkey King Bar artifact, and after upgrading the ability with Aghanim's Scepter, the character becomes even stronger in team fights. The Coup de Grace ultimate allows Phantom Assassin to deal significant damage and instantly eliminate weak heroes. After buing Aghanim's Shard, the hero gains the Fan of Knives ability, which is extremely effective against opponents with strong passive abilities.
Mortred is a member of the Sisters of the Veil order, that considers assassination a sacred part of the cycle of life. The sisters are professional killers, but their motives are not clear as their victims are both figures of great power and ordinary peasants.