It grows with +1/+1 counters, draws cards when you cast 4-power threats, and eventually turns that board presence into direct damage to opponents
Where the card shines, though, is in its overload ability, which lets you cast the card for a higher cost and extends its effect from a single creature to each one you don't control
For example, if you attacked twice with Don & Raph in the same turn without casting any noncreature spells in between those attacks, the next noncreature spell you cast that turn would cost less to cast for each artifact you controlled
Most commonly found in Gifts Ungiven style control decks and Death Cloud based denial decks but not restricted to those archetypes
Maelstrom ArtisanMaelstrom Artisan Well, lets not beat around the bush
Reverse holos from competitive cards like Ultra Ball might fluctuate as new sets release and deck strategies change