Well, it's spoiler time once again and it looks like Oath of the Gatewatch is going to be pretty good to my Type 4 Stack
Kozilek, the Great Distortion

CC (using these until we get a proper colorless mana symbol tag
Legendary Creature - Eldrazi
When you cast Kozilek, the Great Distortion, if you have fewer than seven cards in hand, draw cards equal to the difference.
Menace
Discard a card with converted mana cost X: Counter target spell with converted mana cost X.
12/12
Solid threat right out of the gate! I imagine this is going to take some doing to take down!
Endbringer

C
Creature -Eldrazi
Untap Endbringer during each other player's untap step.

: Endbringer deals 1 damage to target creature or player.
C,

: Target creature can't attack or block this turn.
CC,

: Draw a card.
5/5
Solid board control/card advantage, although it requires you to be able to untap with it or give it haste. Still, the payoff seems big enough to give it a shot.
Sphinx of the Final Word

Creature - Sphinx
Sphinx of the Final Word can't be countered.
Flying, hexproof
Instant and sorcery spells you control can't be countered by spells or abilities.
5/5
Man! This set is all about big scary beaters so far! Like Kozilek, really tough to deal with, which I find is sort of a requirement for creatures who just beat face these days. Protecting all your other spells for counters just put him over the top!
World Breaker

Creature - Eldrazi
Devoid
When you cast World Breaker, exile target artifact, enchantment, or land.
Reach
{2}C, Sacrifice a land: Return World Breaker from your graveyard to your hand.
5/7
This seems like a hell of a replacement for Acidic Slime if you've still got him in your stack. I don't think the recursion is going to trigger that often, but it's not totally irrelevant.
Mindmelter

Creature - Eldrazi Drone
Devoid
Mindmelter can't be blocked.
{3}C: Target opponent exiles a card from his or her hand. Activate this ability only any time you could cast a sorcery.
2/2
Might actually be too strong, but I want to give it a try anyway. The saving grace being how easy the little bugger is to kill, but if it sticks around for any length of time, he just ruins everyone else's hands.
Reflector Mage

Creature- Human Wizard
When Reflector Mage enters the battlefield, return target creature an opponent controls to its owner's hand. That creature's owner can't cast spells with the same name as that creature until your next turn.
2/3
A nice utility dude with a unique take on a classic comes into play trigger. Worth trying out at least.
Mirrorpool
Land
Mirrorpool enters the battlefield tapped.

: Add C to your mana pool.
{2}C,

, Sacrifice Mirrorpool: Copy target instant or sorcery spell you control. You may choose new targets for the copy.
{4}C,

, Sacrifice Mirrorpool: Put a token onto the battlefield that's a copy of target creature you control.
Finally! A non-creature! This will probably sit on the board for a while just waiting, but when it goes off it ought to be brutal! The fact that it doesn't take up a spell for the turn and is so versatile makes this one a definite inclusion in my stack!