mtg card ability rules A magic corner of the Universe: Mana abilities and Caged Sun What Is a Mana Ability

Removing an artifact or creature, even temporarily, provides a powerful boost, if only because you get in an extra attack or two

Karn, the Great Creator

If you're looking for a fun go-wide Equipment deck, I'd highly recommend the Final Fantasy VII precon

Roll two d20 and ignore the lower roll

Even with myriad you're still only getting a temporary advantage, so you should make sure you either borrow something that's going to leave a mark, or lean on sacrifice effects to circumvent giving the creature back

I do like what Talisman bring to the archetype however you have to be careful to not play too many of that sort of thing