Time Stop shenanigans

[bekeleven]

The duration on Time Stop is 1d4+1 rounds of apparent time, and as such, is Persistable, houserules notwithstanding.

Yep. From 1D4+1 rounds in a standard action, to 1D4+1 rounds in 24 hours. It's like an incantatrix's quintessence!

That said, NecroticPlague's solution is the mathematically correct way of dealing with nesting, stacking effects. Basically, treat it as a literal stack, and LIFO.