Robin v. Xander

https://youtu.be/WnY3yCNvH7I
Start off the map attacking the units on the right with BK, instead of leaving him in a position to bait Xander. Use Azura to keep him out of Xander's range.
Use Black Knight to tank a lot of hits.
Nephenee will need to be quite sturdy as well. She'll end the battle with a lower health than BK.
Use Robin's Gronnwolf to off Xander. With his resistance And the tome's Strength against mounted units, she'll overcome the color disadvantage.

Nephenee

Robin (F)

Performing Azura

Black Knight