Whilst this card has the useful Ward keyword - meaning that it cannot be targeted by anything but a challenge - what makes it really shine is its ability: Spare Parts
At the beginning of each end step and when this enchantment leaves the battlefield, destroy all tokens created with this enchantment
If the second ability refers to "the exiled card," it refers to all cards exiled by the first ability and the copy
(Remember I was the man who designed Scragnoth, the first "can't be countered" spell.) In the end, we went with the cleanest, simplest version that coincidentally hosed control decks
As soon as you start factoring in other delve and escape cards the value of Sinkhole starts to dwindle
Back then, most people opening cards were playing the game, and the attitude was, Why would you grade these