We have an Expertise Die (d6) instead of doubling your proficiency.
this is a cool idea.
I am thinking about changing the dice rolled for expertise with a flat skill bonus. +2 sounds nice with raised floor.
IE: expertise, in addition to normal proficiency bonus changes d20 to d12+10.
so IE normal skill check would be with proficiency at 5th level with +4 mod at +7
no proficiency: d20+4, range 4-24
proficiency: d20+7, range 8-27
expertise: d12+17, range 18-29
at max skill level, prof bonus of +6 and +5 ability it would be
no proficiency: d20+5, range 6-25
proficiency: d20+11, range 12-31
expertise: d12+21, range 22-33
I might add skill mastery:
instead of d12+10, you roll d8+16
that would make top skill range d8+27, range 28-35
how to gain skill mastery?
at levels 8+ whenever you gain expertise, you can turn one expertise into skill mastery instead of gaining skill expertise.