Proliferate in ONE was restricted to single-use triggers (except for Tainted Observer, a few mythics, and the reprinted Thrummingbird), which strikes me as a good start
By promising your opponent a gift, you can change up the abilities of your spells
Only spells can be cast while every card type is played. This difference is especially important when looking at cards that allow you to play cards from exile, a function that red cards use in place of draw effects
it's way too rich for me, but it's fun to theorycraft
I could see running Corrupted Conscience over Control Magic if youre already gunning for the poison kill
Theyre part of an elaborate game with a complex set of rules, and any card thats going to give a competitive edge in a game is likely to be valuable