To pull off that trick you need:
Eternity +
Photon/Blightning +
Shard of Readiness +
Animate Weapon +
Electrum Hourglass +
Revolving Time
6 cards combo, dealing minimal damage, still counterable in LOTS of ways (rewind an Eternity to nullify the shard; destroy ANY one of the cards with PC or CC).
This would be a good healing combo for a stall / deckout deck. If a deck hasn't got an answer to this, though, that deck has a problem. Lacking in PC, CC AND (out)rush potential? What are you playing, a starter deck? O.o
Anyway. I don't consider the combo as OP, because it costs a lot, is HARD to pull off, and has not that good of an effect to justify it. Even with 6 of EACH out (a 36 card combo that costs 6
per turn), you're still healing 180 a turn. 6 Feral Bonds, with a full field, heal 138. Potentially, you can pull that off with 7 cards (6 Ferals + a single Firefly Queen or Pharaoh... or Aflatoxin) probably more, but still in the 10-15 range.
Additionally, if you are no FG, healing by more than 100 is rather... useless. Stone Skin and SoD excluded. But... yeah. We have enough exceptions as is. I can't think of this single combo being OP. It may be worth a deckout deck around this. MAYBE.