Fearsome cards galore include Memory Jar, Grim Monolith, Iron Maiden, Palinchron, Crawlspace, and Defense Grid
Opportunity awaits
The black-green Elf Noble is a 2/3 with menace, so shes tricky to block, and whenever she connects with an opponent you create one 1/1 Elf Warrior for each point of damage she dealt
And black creatures flipped whenever a creature was put into the graveyard
The cycle of Sword equipment is probably the most famous one and took decades to finish, having cards in Darksteel (2004), Scars of Mirrodin (2010), Mirrodin Besieged (2011), and even in Phyrexia: All Will Be One (2023)
This takes very little work to make obnoxious, and you only have to get a couple of cards out or a buff or two to make this ability very absurd indeed