Vigilance, haste
As Saskia the Unyielding enters the battlefield, choose a player.
Whenever a creature you control deals combat damage to a player, it deals that much damage to the chosen player.
If Saskia leaves the battlefield and returns, you choose a player again. It doesn’t remember the previously chosen player.
If a creature you control deals combat damage to the chosen player, it deals that much damage to that player again.
Once the chosen player has left the game, Saskia’s triggered ability will have no effect.
The damage that Saskia’s ability causes a creature to deal isn’t combat damage.