Piru

Piru was an Elder Dragon and the life-partner of Chromium Rhuell and mother of Crosis.

History
Piru was one of the Elder Dragons, creatures spawned by the Ur-Dragon when Dominaria was young. With her mate, Chromium Rhuell, she birthed entire nations of dragons, including the primeval dragon Crosis, the Purger. Piru and Chromium were among the very few Elder Dragons who survived the Elder Dragon War instigated by Nicol Bolas.

Millennia later, both Piru and Chromium were servants of the planeswalker Geyadrone Dihada and were summoned by her to fight the planeswalker Dakkon Blackblade. Dakkon tried to put mind-control on Rhuell and ordered him to kill Piru; but, since Elder Dragons are nearly as powerful as planeswalkers, Dakkon failed.

Rhuell started to drain away Dakkon's energy but was sent to an unknown location by the planeswalker at the last moment. Piru then fought him but was killed when Dakkon stabbed her with the Blackblade, causing the release of a massive energy blast that created the Dueling Chasm of Golthonor.

Geyadrone Dihada absorbed much of Piru's energy and had, in fact, planned the dragon's death all along; she wanted the power of an Elder but knew this could only be gained when such a dragon died. Since they were almost impossible to kill, she had Dakkon forge the Black Blade and then manipulated him into fighting and killing Piru.

Note
There used to be some debate whether Piru was a true Elder Dragon, or just one of their direct descendants. Some sources say there were only five Elder Dragons that survived the Elder Dragon War: Chromium Rhuell, Nicol Bolas, Palladia-Mors, Vaevictis Asmadi and Arcades Sabboth; which would suggest that Piru was not. Some of later Magic comics, however, claimed that Piru was a sixth Elder Dragon. Furthermore, Piru seemed to be colorless, making it the "sixth color" not represented in the others.

When the Blackblade resurfaced on Dominaria, its legacy was remembered as being the weapon that killed an Elder Dragon, thus rendering the discussion of Elder vs Non-Elder moot. The Elder Demon Belzenlok took credit for that victory upon receiving the blade.

The debate was definitively decided when her card from Modern Horizons 2 featured the type line Elder Dragon. Piru's colors were also clarified by the card, which represents her as red-, white- and black-aligned.

Trivia

 * Piru is a Finnish word for the Devil.
 * Piru is Brazilian Portuguese slang for a penis, requiring her name to be changed to Pairoo in the Portuguese localization of the card.