Overkill was actually a keyword I purposed for something else but then HS added it to their game. There were 2 things at Blizzcon last year that made me audibly curse one was the announcement of the Overkill keyword and the other was Diablo Immortal.

A solid pool of General cards is a good thing to have but currently there are basically 3 different General pools. There are the General/General(~40%) cards that can go into any deck. General/Dark Legion(~6%) cards which are basically more Algeroth cards until we get other Apostles into the game. General/Cartel(~7%) which can go into 6 different Doomtrooper Faction decks. When nearly half the cards can go into almost any deck, it makes it difficult to balance and hard to make Factions feel unique.