While you could try to play Thrumming Stone with MTG cards that ignore deck limits, theres a lot less room to include the cards in smaller decks
Beregond of the Guard buffs your entire board any time a Human enters the battlefield
For the cost of one white, +2/+2, flying and lifelink is an incredible buff that can grant you an unexpectedly substantial lead
Another perfect example of this is Isshin, Two Heavens As One, which reads: "If a creature attacking causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time." This is an incredible ability to have on a commander - and building a Commander deck around it is sure to be a blast - but in a Standard set it just feels off
Charcadet Promo ($80+) Fire-type ETB promo evolving to Armarouge/Tyranitar
Ironically, the reason I scrolled the comments page was to get to the comment box to give MGK props for the Atzalan reference