This is how the sahuagin priest proves (to me at least) that Iceheart is Shiva. The Ascians granted the priest the power of the Echo, granting him immortality (for however long that lasted). Players are also granted the Echo and when we die we can just revive at an aetheryte like nothing happened. Remind you of anything? (/cues Jeopardy theme) That's right, like a primal. Primals don't die, they just go to the aether and have a nap. Imagine if Echo bearers had the same strength of spirit. Seems to achieve this you just need alot of aetheric energy. Iceheart is either naturally gifted with the Echo or has been/will be awakened by the Ascians, then she'll go and power up on crystals cause why not and in the process become Shiva. That's my theory, at least.