Fraying Sanity
Oracle Text
Enchant player
At the beginning of each end step, enchanted player puts the top X cards of their library into their graveyard, where X is the number of cards put into that graveyard from anywhere this turn.
Card Rulings
7/14/2017 Fraying Sanity’s triggered ability counts the number of cards that were put into the enchanted player’s graveyard during the turn, even if Fraying Sanity wasn’t on the battlefield at the time those cards were put there, and even if those cards have left that graveyard.
7/14/2017 The value of X is determined only as Fraying Sanity’s triggered ability resolves. For example, if three Fraying Sanity Auras are attached to one player who had four cards put into their graveyard this turn, X will be four for the first ability to resolve, eight for the second, and sixteen for the third.
Sure, it needs things to enable it in Standard, but Limited is totally different. Most decks will be 40-45 cards. You need no enabling. You just need to play in a competent manner and this card turns into a 10-turn win clock. The only drawback is that you may help them find their Aftermath cards. But that's not terribly bothersome.
2 of these and one startled awake
1 of these and 2 startled awake
Either of those two scenarios is a t5 win, which isn't too slow for standard.
Also going to pray I get this for prerelease. Seems great in a 40 card deck format that contains winds of rebuke, compelling argument and cycling.