Dead power

The term dead power was used to refer to a dead deity.

Deific Death
Deities were not wholly immortal; it was possible for them to be killed, though they were also known to come back from the dead. As a general rule, though a deity could only be slain in their home plane, by another deity (except for demipowers, who could be killed by exceptionally powerful mortals). Deities could also fade away and apparently die when they were forgotten. The Time of Troubles provided a temporary exception to these rules, however. A deity could also seem to die if their connection to a given sphere was severed.

The sheer power and responsibilities of a deity were typically passed or taken by their killer. However, if the killer was incapable of taking up the power, it was instead split amongst the next most suitable deities in the pantheon, or, if the dead power's portfolio was a subset of a more powerful deity's portfolio, then their power passed to their superior.

Deific Dead
When a deity was actually dead, their body was mystically transported to the Astral Plane, to drift there for all eternity. Such bodies were largely inert, save for occasionally seeming to stir as if asleep rather than dead.

Sometimes, the memory and personality of a deity was separated from their power and true form at the moment of their death, typically by the interaction of the magical turbulence of their death with the magic of a powerful relic or artifact into the same area. In such cases, the deity remained awake but imprisoned, in a sense, though vastly uncomfortable with their much-reduced state.

Deific Resurrection
While it was theoretically possible for a deity to be utterly destroyed, in practice, deities were more than capable of returning from the dead. One way this could occur involved a great deal of worship and a long ceremony with many offerings. Additionally, in Toril, Ao had the final say over whether a deity of that sphere could return to life. However, newly-risen deities were not more the demipowers in might.