The subject of this article originates from non-canonical sources. To find out about what is considered "canon" see LOTR:Canon.
The Summoned Dragon is a beast in the game The Lord of the Rings: The Battle for Middle-earth II and its expansion. It is a dragon that can be deployed by Isengard and the Gobin faction.
In The Battle for Middle-earth II, the dragon is a spiked-body dragon with either golden, grey and maroon skin, but in The Rise of the Witch-king, the dragon is scaly bearded dragon with either white or blue-grey scales. Both dragons breath blue fire, possibly hinting that it could be a special drake, and when flying off, it uses a black misty cloud to conceal itself.
This dragon only appears only in The Lord of the Rings: The Battle for Middle-earth II and its expansion The Lord of the Rings: The Battle for Middle-earth II: The Rise of the Witch-king, as a summon-able power than mentioned before, can be used by both Isengard and the Goblins faction. During the Evil Campaign or a Skirmish, you can summon the dragon for 25 points during Tier 4 for an estimated time-limit.
During Mission 8 of the Good Campaign, the Summoned Dragon appears as one of the commanders that was in the battle while defending Dol Guldur, but was eventually killed by the united armies of combined elves and dwarves. In The Battle for Middle-earth II, the power's icon is consisted of the red-brownish dragon, however in The Rise of the Witch-King, the icon is consisted of the dragon in white-blue scales.