Xathenos is fun, but not worth the extra crafting cost.
Its actually a pretty decent troop if paired with another True Damage dealer and if you’re not relying on it to summon troops to win games. Once it casts 2-3 times, it’s a troop worth acknowledging.
Its biggest problem is its first cast takes too long for its damage output.
Key issues: Mana cost, bad 3rd trait. (so mainly, its identity)
Something like Enchant all Undead Allies on 4 or 5 match would go a long way to making this troop more interesting.