Ceti Eel

Artifact-graveyard lists may test a large Eel, but four mana for a non-evasive creature with no immediate value is far below Modern's rate.

Could be wrong if A dense artifact self-mill shell could make it consistently enormous enough to justify a niche slot.

Ceti is much slower and less reliable than Barrowgoyf; a four-mana one-shot stat creature is not a credible Legacy payoff.

Could be wrong if An existing artifact graveyard shell could value its unusually large ETB scaling more than expected.

Affinity can stock artifact cards and test it as a large threat, but unlike Writhing Chrysalis it gives no extra body or immediate board value.

Could be wrong if Its average ETB size may be too small after normal graveyard hate and artifact recursion.

It can enter large in artifact-creature graveyard decks, but is a four-mana vanilla body without evasion, recursion, or card advantage.

Could be wrong if Dedicated self-mill lists may reliably make it large enough for its cheap creature payoff to matter.

At four mana it will often mill into a 3/3 or 4/4 and can grow larger after trades; that is a solid common body, not a bomb.

Could be wrong if Unknown creature density, archetypes, and removal could leave it too often as only a 2/2 or 3/3.