MTG Salvation

Seems like a decent land. Could definitely see printing once Phyrexia takes over Kaladesh, but maybe with the ability to convert energy into colored mana as well? Something like a mix between Aether Hub and Unknown Shores?

There hasn't been a proper blue fatty in a while.

Screeching Skystalker 3UU
Creature - Leviathan (Rare)
Flying
Play with your hand revealed.
Screeching Skystalker gets +3/+3 for each land card in your hand.
Its shrieks erode stone and steel faster than any winds or waters.
1/1

Votes: Rocco, Indighost

Stasis Ooze 2GG
Creature - Ooze (R)
Devour 1 (As this creature enters the battlefield, you may sacrifice any number of creatures. This creature enters the battlefield with that many +1/+1 counters on it.)
If Stasis Ooze would devour a creature, exile it instead of putting it into its owner's graveyard.
When Stasis Ooze dies, return each creature card exiled with it to the battlefield under their owner's control.
2/2

Seems like a very powerful spell, but it's niche enough for it to be acceptable.

Minadra's Prodigy 2RR
Creature - Human Wizard (Rare)
Flash
When Minadra's Prodigy enters the battlefield, put target spell or ability on top of the stack. (A spells or ability on top of the stack is the first to resolve.)
"We all move through time. Mistress Minadra has simply taught me to move through it faster."
2/2

(Minadra is a mono-R planeswalker that is fascinated with time travel and manipulation. She has a very Izzet-attitude, wrecking havoc by experimenting with volatile and yet unexplored forms of magic, just like this card, she tries to do things that haven't been done before.)

Simic Tidespinner 3GU
Creature - Merfolk Spider
Reach
Whenever Simic Tidespinner blocks one or more creatures, those creatures don't untap during their controller's next untap step.
Tap an untapped Spider you control: Simic Tidespinner can block an additional creature this turn.
2/5

Next:
Zombie Spirit
Construct Avatar
Angel Werewolf

Beasts are usually 3/3s, the go-to 2/2 green token is a Wolf. The -1 is fine, but the ultimate feels a bit bad to me. Sure it's a decent effect on an emblem but it'll be turn 7-8 at least before you can ultimate, at which point you've probably played most of your lands. Something like "Search your library for any number of basic lands and put them onto the battlefield tapped" would be a hell of a lot stronger and would definitely make it seem more playable.

And now for another green mythic

Siege's End 3GG
Sorcery (M)
Destroy all artifacts, enchantments, and creatures with defender.
"There is nothing that has been built that cannot be taken apart."
- Gallad, Siege Commander

Day's Undoing and Glorious End

Dramatic Appearance 2G
Sorcery (MR)
Put a creature card from your hand onto the battlefield. End the turn. (Exile all spells and abilities on the stack, including this card. The player whose turn it is discards down to his or her maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Honed Kopesh 3
Artifact - Equipment
Equipped creature gets +2/+0 and has Double Strike
Equip 2

Cemetery cultivator has a really cool effect. Because it's so limited in its capabilities, I think having it give two mana of any color allows it to branch out more with very change.

Planeswalker time!

Liza the Witch 1RG
Planeswalker - Liza (M)
[+1]: Exile the top card of your library. You may play that card this turn. If you don't, Liza the Witch deals 2 damage to you.
[-2]: Liza the Witch deals 2 damage to up to two target creatures. If a creature dealt damage this way would die,, exile it instead.
[-5]: You get an emblem with "At the beginning of your upkeep, create a 6/6 red and green Gravespawn creature token with trample and haste."
Starting Loyalty: 2

Altar of the Void 3
Artifact
Whenever you cast a spell with converted mana cost 0, target player loses half of his or her life total, rounded up.

Leyline of the Collective 2GG
Enchantment
If Leyline of the Collective is in your opening hand, you may begin the game with it on the battlefield.
All nonland permanents are tokens.

Next: Márton Stromgald

Jotun Dragonfeller 5WW
Creature - Human Soldier Archer
Vigilance, Reach
W, T: Destroy target creature with flying.
5/5

Dreamwarper 1RR
Creature - Viashino Shaman
Haste
R: Switch target creature's power and toughness until end of turn.
3/1

Morwani, the Nurturer 4GG
Legendary Creature - Treefolk Avatar
Protection from black
If a Plant, Saproling, Forests or Treefolk you control would be destroyed, regenerate it.
3/7

Infinite Possibility 6UU
Sorcery
Draw card equal to the number of cards in your library. Discard your hand at the beginning of your next end step.

Next: Wake the Reflections

A common Bolt variant is always going to be strong, even with such a drawback. Depending on the rest of the set, it could be fine as a common or might need to be upgraded to an uncommon.

Also in defense of Ilal: I just realised how silly putting deathtouch on the rat tokens actually was. I was imagining him trading creatures one rat at a time and wanted to give the opponents a better time. I might make you lose life for the rat tokens, or swap the cost to XXUB.

Either way:

Brightrock Mason 1GW
Creature - Human Soldier (Uncommon)
When Brightrock Mason enters the battlefield, search your library for a basic land card or a creature card with defender and reveal it. Shuffle your library and put that card on top of it.
"A good wall, like a good city, depends on its foundation."
2/3