Cards like Deeproot Elite, Kumena, Metallic Mimic, and Branching Evolution all keep the counters coming, while cards like Sage of Fables and Tributory Instructor turn those counters into cards
Ursine Fylgja Coldsnap s Ursine Fylgja is one of two total cards to mention healing counters, the other being Ice Age s Fylgja
Id keep an eye to see if Body Count is good enough to make its way into more competitive places like CEDH or even (heaven forbid) Legacy
Many Magic players widely recognize and agree upon established cards for each format, and some cards see use in many formats
At instant speed you can either tap anything, even a land, at instant speed and draw a card, or then you can deal two damage split across up to two targets, so it's a powerful instant speed removal or tempo trick and can draw a card to replace itself
Because of this, decks like these require a higher land count than decks with a lower mana average