Changes Enduring spells and Greater Enduring Spells mythic abilities to be the following
Enduring Spells
Prerequisite: Metamagic (Extend Spell)
You've learned a way to prolong the effects of your beneficial extended spells
Benefit:
Effects of your spells on your allies cast with extend metamagic applied that should last longer than 1 minute but shorter than 10 minutes last 10 minutes.
Effects that should last longer than 10 minutes but shorter than 1 hour last 1 hour.
Greater Enduring Spells
You've mastered a way to prolong your beneficial spells.
Benefit:
In addition to existing benefits effects of your spells on your allies cast with extend metamagic that should last longer than an hour are permanent.
Unlike base game where "longer than X" is "longer or equal" here it's actually longer as written.
So 1 minute extended spell will stay 1 minute. 1 minute 12 seconds will become 10 minutes.
Cave Fangs, Call Lightning, Call Lightning Storm won't become permanent. Sorry if you already theorized this.
Does not introduce save dependency, so you can remove it any time.
If used together with Tabletop-Reworks, it will overwrite TT-Reworks changes to Enduring Spells.