Alduir NightBlade (nee Terrafin) is the grandmother of Ender and the brothers of Ender, the great-aunt of Malice, and is named after a mythical dragon of death. She is very much dead. Ender and co. once got some vague advice from her ghost on where to find the twelfth of the Master Gemstones (the Diamond was hidden inside Ender).
As most spirits do, she speaks in riddles regularly.
Deep within the towers tall, a stone with magic powers all. A choice to make, is theirs alone, but time is never set in stone. - The riddle told
- the towers tall - The Portal Towers, where the stone was found
- magic powers all - The Master Diamond is all-powerful
- A choice to make, is theirs alone - Ender had to sacrifice himself to save everyone, and of course everyone tried to stop him
- time is never set in stone - Ender was able to bend time and space to return to his friends