I have a question about the DCs I should set as a GM when my Thaumaturge player uses Exploit Vulnerability. Quoting the source, it says "Select a creature you can see and attempt an Esoteric Lore check against a standard DC for its level"
My question is about the use of the word "Standard". It implies to me that regardless of the rarity of the creature, I should use the default level-based DCs. For example, the party will soon be coming upon Doppelgangers. Doppelgangers are level 3 creatures, which means a Recall Knowledge check against them would normally be 18. However they are an uncommon creature, so the DC is 20.
Would a Thaumaturge's Exploit Weakness check against a Doppelganger be 18 or 20?