Losing a creature a turn is a hard pill for an opponent to swallow, especially once it costs you no investment past the initial one mana and one card
Giving your artifact creatures flying/lifelink can be strong, but you have to be built for proliferation effects, artifacts, and payoffs for the actual counters from proliferating
PleasantKenobi put it succinctly on Twitter: Am I going crazy, or is all of the content around Final Fantasy ignoring the price hike
Proliferate has always been a boon in these types of decks, and now with the mechanics card pool nearly doubled, we should expect to see counters happening even more
And also every cEDH deck, but, well, cEDH players love Rings that go into every single deck
Savage Thallid Savage Thallid is the timeshifted Feral Thallid, this time one mana cheaper, a little weaker, and with the missing Saproling-creation ability