In Tempest, it was turn one (Mogg Fanatics, shadow creatures, and flyers), Invasion turn two (2/2 bears for every possible color combination plus several one- and two-mana apprentices and utility creatures), and Mirage turn three
Access to 6 of MTGs most iconic spells is incredibly powerful, and while only Braingeyser and Regrowth see consistent play in the format (though Black Lotus absolutely would if it was legal), Terror, Disenchant, and Shivan Dragon can all still be very handy
Whenever an attacking creature dies, each opponent loses 1 life and you gain 1 life
Another neat trick most people overlook with Conjurer's Closet / Thassa, Deep-Dwelling is that the exiled creature returns under your control, not the owner's control
Great choice
Creature - Human Rogue Ravenloft Adventurer When this creature enters, you take the initiative