It's a very powerful card, giving our Sliver creatures some protection in the form of indestructible
Those effects are particularly good for this deck's stun and shield counters, keeping opposing creatures locked down and your own creatures safe, as well as for blitzing through the strong effects of your saga creatures
One way WotC can achieve that is by reprinting cards that are in unusually short supply
These decks typically play game-ending legends like Emrakul and Atraxa, dumping them early and reanimating them for an easy win with their namesake card
Winter, Misanthropic Guide Bitter, jaded, and cynical, Winter has managed to survive for over a decade using only his intellect after being trapped within the House's walls
Even in Vintage, the only place this card is available to play, it is restricted (you can only have one copy of it in your deck)