Good Ol' Gwenyth!

Just don't attack with her. Bad idea.

Gwenyth the Bard (Birthright, 100/100): Here's the first example of a card which is fairly mediocre in standard Spellfire, but becomes a powerhouse in TAV, especially in a one-on-one game of TAV.

In Standard, a player can attack with many different champions, potentially overwhelming an opponent until the defender is out of support cards. Then comes the coup-de-grace from an especially formidable attacking champion. Cards like Gwenyth here are of limited value because they can only stop one champion from attacking. 

In TAV, things are different. Because the attacker can only swing (to borrow a Magic: The Gathering term) with one champion per turn, Gwenyth can stop the best champion in the attacker's pool from coming over to bug you. Of course, she can't stop a champion played from the hand directly into combat, but once that round is over, even if it's a loss for the defender, the champion returns to its pool, where Gwenyth can step all over it next turn.

Since players can come from behind much more easily in Spellfire than in Magic (and even more so in TAV than in Standard), losing one round - and one realm - is not a backbreaking event. Gwenyth can switch champions each turn, making her valuable in a multi-player game of TAV as well.

Personally, I love having Gwenyth in my pool. Like Hettman Tsurin, The Noble Outlaw, and Lyr of the Mists, Gwenyth attracts champion-killing events and spells, weakening an opponent's hand. Conversely, if the opponent chooses to let Gwenyth sit there, she can evolve into a royal pain and a serious problem. I have seen her stop the Living Wall, Iuz the Evil, and Istus, Lady of Fate.

An opponent with one of these primo champions sitting uselessly in his or her pool is well on the way to defeat in TAV.

Gwenyth is also of low level, good for defense especially when combined with instant-kill cards like Loup-Garou or Noble Djinni (all instant-kill cards are immensely more valuable in TAV than in Standard).

I'd love to read your comments on this underrated card!