2006: Dread Return from Time Spiral At first glance, Dark Depths seems like the easy pick for most broken card of 2006, considering its power in Legacy and its ability to make a 20/20 indestructible flying Marit Lage token as early as Turn 2
King Suleiman ($161) King Suleiman was probably quite good when it was first printed, and djinn/efreets were more common to see, but these days its just pure nostalgia (and Reserved List, obviously!)
Ellivere herself creates Virtuous enchantments, giving creatures +1/+1 for each enchantment you control - a potentially massive buff
Rakdos the Defiler Rakdos the Defiler forces everyone to sacrifice permanents
While that does require tapping, it is mana free, and a nice card boost, mana boost, life loss for your foe, and more