One thing that 40k the game has that Commander doesn't really, is the ability to create your own heroes (or villains) and equip them with various wargear or abilities that belong to the tradition of those factions
Of the generic tribal cards you list, I like Obelisk of Urd, which has been good in my cube, the rest is meh, because you really need a tribe for them to do anything
Szarel, Genesis Shepherd Running Szarel, Genesis Shepherd means playing lands from the graveyard for endless value
Weiss Schwarz by Bushiroad is the premier anime trading card game, featuring licensed sets from the biggest anime, video game, and entertainment franchises
Ephemerate Probably too strong for Pauper (though Im far from an expert on that), Ephemerate is a fantastic cheap piece of interaction