Bansmareton is the only psionic avatar champion thus far in Spellfire. It is very useful, but at the same time, isn't worth it.

The price for Bansmareton is discarding a psionic champion from play, meaning any champion able to use psionic powers cards, not necessarily as psionicist, which works very well with his champion type. Each opponent being able to draw a card when Bansmareton enters play is very bad for card advantage, and thus needs a very powerful power to balance.

Bansmareton's power is very strong and should be considered, as he acts as if he was every Underdark realm, allowing all of his player's champions (not just the psionic ones) to attack any realm regardless of position or movement restrictions (including requirements required by other cards, like Song of the Dragonlance (22/DU).

It doesn't get around "requirements" type cards (Den of Thieves (24/NS-chase) or Anytown, Anywhere (70/4th)) or non-movement requitrements (like the Ruins of Zhentil Keep (3/3rd) requiring clerics to attack).

Each deck must choose for itself whether the card advantage loss is worth this nice advantage of attack. You should expect to see this card in psionic based fun decks, but it will be suprising to see it in tournaments. Its lack of defensive powers means finding ways to protect Bansmareton are highly recommended if you intend to use him.