opponents draw cards mtg Five essential card for Commander Mind's Eye | The Brothers'

(Create an Incubator token with X +1/+1 counters on it and ": Transform this token." It transforms into a 0/0 Phyrexian artifact creature.) At the beginning of each end step, if a Phyrexian died under your control this turn, proliferate

Some trigger when something else happens during the battle e.g

While Standard presented the challenge of unfamiliarity, Modern had the opposite problem

Wizards seems not to want to include these in Secret Lairs, and they may want to keep them to hype up booster boxes to sell packs

It's probably only a matter of time.

Since it phases out, it can save you from exiling removal like Farewell