We did have five mythic rare "secret identity" TDFCs and five Sagas representing famous Spider-Man stories, but very little else about this initial structure remains in the final set
(2025-06-06) The value of X is calculated only once, as The Final Days resolves
It serves as a (very) minor combat trick, and a way to convert a creatures power into +1/+1 counters on another creature if the first one dies
Linvala, Keeper of Silence on its own provides a similar effect but with less upside
Although it is somehow anchored in the flavor and helps the commander occupy a special place among the other cards, in my opinion, it serves more as an ornament that adds to the other qualities highlighted by the previous rules
But here, you must calculate the steps to find the most opportune moment to use the spell