I was already loose for Amass cards
Several factors force Bracket 4 or higher: mass land destruction (Armageddon, Obliterate), Fast two-card infinite combos like Thassas Oracle + Demonic Consultation, or very high combined power signals across fast mana, tutors, and combos
But restricting the other abilities to zombies keeps it from having broad application
the only caveat is that you absolutely want to mill it or loot it away, as this blue creature becomes much more powerful when escaped from your graveyard
However, one strategy in the game can mill cards with its first attack, but it can also disrupt the opponent's bench if it can set up enough energy throughout the game
The base set of the upcoming blocktimed alongside the release of Pokmon Legends: Z-A is already shaping up to be one of the most stacked in recent memory