End game summons idea

One thing I've always wanted was to be able to use specific minions in the endgame, but with the power of an endgame summon.

Wouldn't it be cool to be able to use the twins or some other summon you liked?

My idea is to create an endgame staff that allows you to attach any staff from the game to it and summon an updated version of the summon, making it usable again. What do you think?