The dragon champion borrowed by Verminaard adds its adjusted level to Verminaard's like a normal ally, however it's special powers do not function for Verminaard. This does not negate any immunities that the borrowed champion has, the immunities just do not extend to Verminaard and any of his other attached cards. Win or lose, the borrowed champion returns to its original pool at the end of the battle. If the borrowed champion is somehow discarded before the battle is resolved however, it is discarded.

A good example of a card that would do this is Clay Golem [4th-247]. The borrowed champion is considered an ally for all cards that affect allies. Verminaard gains the 4 levels for having Tiamat, God of Evil Dragons [DR-44] or Takhisis, Queen of Darkness [DL-33] in play no matter who has them in play. If both are in play, Verminaard still gains just 4 levels. Remember that champions can be involved in combat only once a player turn, no matter if used as champions or allies. This is a good way to leave your opponent champion short in combat. You must wait until you can legally play an ally (i.e. you are losing and can play a card) before you can activate Verminaard's power. Verminaard is not considered a dragon for cards that affect dragons. His name is Dragonmaster, all one word.

If both Tiamat and Takhisis are in play, Verminaard still only gains 4 levels in total.

When Verminaard uses a dragon champion as an ally, he only gains the level bonus of the champion/ally, including any attached cards. Verminaard does not benefit from any special powers of the champion/ally or any attached cards. The champion/ally does retain any immunities it may have, but these immunities are not transferred to Verminaard.

The borrowed champion only returns to its pool if it is still in play at the end of battle. Cards that destroy allies during battle, such as Airship or Brine Dragon, would cause the borrowed champion to be discarded immediately and not return to the owning player's pool.

Verminaard cannot bring an ally into play until the player is losing the round of battle, just as cards cannot be played unless a player is losing the round.