Liliana, Untouched by Death | Rooftop Storm | Ratadrabik of Urborg (and one other card)

Cards

Ratadrabik in hand or in your graveyard.
Liliana has at least three loyalty counters on it.

Activate
Liliana's third ability by removing three loyalty counters from it, allowing you to cast Zombie spells from your graveyard this turn.
Cast
Ratadrabik either from your hand or from your graveyard by paying ({0} magic symbol) .
Ratadrabik enters the battlefield, triggering
Necroduality, creating a token copy of
Ratadrabik.
Put the original
Ratadrabik into your graveyard due to the legend rule.
Each other copy of
Ratadrabik triggers, creating a nonlegendary token copy of
Ratadrabik that is a 2/2 Zombie in addition to its other types.
Repeat from step 2.

This combo has been estimated to be Exhibition (Bracket 1+).