Piru

Piru was the lifepartner of Chromium Rhuell. The two of them where servants the planeswalker Geyadrone Dihada and where summoned by her to fight Dakkon Blackblade. Dakkon tried to put mindcontrol on Rhuell and ordered him to kill Piru, but since Elder Dragons are nearly as powerful as planeswalkers, he failed. Rhuell started to drain away Dakkons energy, but was sent to an unknown location by the planeswalker at the last moment. Piru then fought him, but she was killed when Dakkon stabbed her with the Black Blade. This released a humongous energy blast that created the Dueling Chasm of Golthonor. Geyadrone Dihada aborved a lot of Piru's energy and had infact planned the Dragon's death all along: she wanted the power of and Elder, but knew this could only be gained when such a dragon died. Since they where almost impossible to kill, she had Dakkon forge the Black Blade and then manipulated him into fighting and killing Piru.

Lesser Elder or Elder Dragons?

There is some debate whether Piru was a true Elder Dragon, or one of their direct descendants: a Lesser Elder. Some sources say there where only 5 Elder Dragons that surived the Elder Dragons Wars: Chromium Rhuell, Nicol Bolas, Palladia-Mors, Vaevictis Asmadi and Arcades Sabboth. This would make Piru a Lesser Elder. However, other sources claim that there are more, something that would be likely since it seems odd that a race as powerful as the dragons could grown from 5 close relatives (Those five are all sibling, safe for Asmadi, their cousin).