The idea of a ‘group check’ is in the rules anywhere in 5e, or is your homebrew rule?

Why Forge cleric does not gain martial weapon proficiency, but is able to use Blessing of the Forge on a martial weapon?

Druid’s Wild Shape, it says you “retain any abilities given by your class/race” : could I still use psionic powers?

Which attribute is used for the banshee’s corrupting touch?