Yu-Gi-Oh: 10 Most Powerful Unbanned Cards In The Game
5. Super Polymerization
Super polymerization is like the original Polymerization on super steroids.
By discarding one card Super Poly allows you to fusion summon a monster from your extra deck using monsters from EITHER side of the field! So you can't use materials from your hand but you can use monsters your opponent controls.
This means if you know the metagame well you can kit out your extra deck to combat any monsters your opponents could play or counter any board they may make.
The real strength in Super Poly is it can be played at quick-play speed at the end of your opponents turn AND your opponent can't respond to its activation.
Similar to Dark Ruler No More once activated that's it, no chance to respond or chain a monster effect. This means your opponent just has to watch as you use their monsters as material for one of your fusion monster (that's likely catered to beating there deck).
The argument against Super Poly is how it's a no skill card that punishes people for playing their deck to the best of their ability. Duelist A spends all day memorising the combos of their deck and should be rewarded, duelist B simply plays Super Poly and there goes all their hard work. The reason for banning it is its very hard to play around, promots little interaction and is super punishing to new or returning players.