Read our primer article about what a prerelease is like, and prepare for your first prerelease, or hundredth
Fifteen is a whole lot of toughness and protection from spells rules out the majority of the cube answers
Promotional items based on the formats you play during a given season (for example, drafters could get a phantom draft, Legacy players could get free entry into a Daily Event, and sure, Standard players could get a hot new card when appropriate)
You probably want to add a heap of effects that look for your creatures entering, a helping of effects that can double up your triggers, and to top it all off you can add a dash of the dash mechanic
However, the sheer power of this card cannot be denied, and having easy, reliable access to it via the Command zone places in near the peak of Modern Horizons 3s options
The sacrifice part of Joo Dee's ability happens as part of the resolution of the ability