If more than one player in a group presses There is no multiple benefit for the group, just the bad personal suspension .. only one single Critical Thinking applies on the group players. Easy to test: Group with more than 2 klicked runes.. potency does NOT rise for 5600 each klciked rune
The passive effect is the same for multiple versions of this rune also. There is no reason to upgrade for the passive effect.
I havent double checked, but from what I was told the 'higher tiers' of the castable charms decreases the reuse timer, which.. who cares, because none of them are good for clicking really.