As a longtime Soulflayer fan, I havent ever had the motivation to jump through the hoops to make it or similar cards work in Cube, and Indominus Rex is just easy mode in terms of offering that sort of play experience
Legendary Creature - Praetor Phyrexian Mystic Remora Cumulative upkeep (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays
This first set is all reprints, but two great board wipes with amazing new art are a good start, even if they arent expensive cards
It doesnt matter if any die, as they replace themself
If an ability tries to move a stun counter from a permanent an opponent controls to another permanent while you control Fear of Sleep Paralysis, that counter won't move
When Fabled releases, cards from the first four sets will not be legal to play in Core Constructed