These cards include beautiful Delta Species printings, E-Reader gimmicks, and holographic cards that have that gorgeous foiling
You essentially get to flicker one creature twice each turn, which might be incredible but its usually mediocre
For example, take the Magic booster
A sweet card that is very abusable in Commander
it says Until end of turn, target creature (not target attacking creature) gains trample and gets +X/+X, where X is the number of attacking creatures (not attacking creatures you control). It once lived in my Cube as a cute defensive trick, allowing my otherwise shrimpy team to stand against their largest attacker
Different cards can create Lander tokens, which are artifacts that can be sacrificed to search for a basic land card and put it into play, tapped