>
Leyline kills/stops/slows:Long explanation:
Ichorid - Either they have an enchantment removal/bouncer maindeck or it's autolose at all. Bridge from Below will NOT hit GY and therefore they cannot produce soooooo many 2/2's. Ichorid won't also hit GY so it can't be animated.
Stax - Welder becomes a Mon's Goblin Raiders. Crucible of the Worlds turns into nothing other than additional mana for Tolarian Academy or an attacker made possible by Karn.
Flash - Obviously, their combo won't work.
Storm - Yawgmoth's Win/Will will not work therefore they should chain/find more spells (9+ in case of Tendrils of Agony).
Toolbox Fish - Skullclamp won't draw them cards. They will run out of gas trying to counter/answer your threats.
Short explanation:
LotV basically slows down/stops any deck that utilizes GY.
It should be
Maindecked based on my experience.
>
At Jotun Grunt:Brings back your resources. Together with the help of shufflers (Fetches and Tutors), you have the chance to reuse them.
Empties your opponent's GY. Too many Dark Rituals and worried about Yawgmoth's Will? No problem. Wasteland + Crucible pinning you down? No problem. Too many Bridge from Below, Ichorids? remove them.
plus, it's a 4/4 beater.

>
At Negator.Yes it is risky. But he is one big tough guy. Unless your environment has aggro, he is pretty hard to deal with.
>
Swords wins over Grasp.Oh, additional suggestion:
Dark Confidant. Very powerful card advantage. Tried and tested.