Have

Whalebone Glider

{2}, {T}: Target creature with power 3 or less gains flying until end of turn.

Balduvian Rage

Target attacking creature gets +X/+0 until end of turn.
Draw a card at the beginning of the next turn's upkeep.

Hibernation's End

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever you pay Hibernation's End's cumulative upkeep, you may search your library for a creature card with mana value equal to the number of age counters on Hibernation's End, put it onto the battlefield, then shuffle.

Bull Aurochs

Trample
Whenever Bull Aurochs attacks, it gets +1/+0 until end of turn for each other attacking Aurochs.

Gorilla Shaman

{X}{X}{1}: Destroy target noncreature artifact with mana value X.

Tinder Wall

Defender (This creature can't attack.)
Sacrifice Tinder Wall: Add {R}{R}.
{R}, Sacrifice Tinder Wall: It deals 2 damage to target creature it's blocking.

Snow-Covered Mountain

Rimehorn Aurochs

Trample
Whenever Rimehorn Aurochs attacks, it gets +1/+0 until end of turn for each other attacking Aurochs.
{2}{S}: Target creature blocks target creature this turn if able. ({S} can be paid with one mana from a snow source.)

Giant Trap Door Spider

{1}{R}{G}, {T}: Exile Giant Trap Door Spider and target creature without flying that's attacking you.

Earthen Goo

Trample
Cumulative upkeep {R} or {G} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Earthen Goo gets +1/+1 for each age counter on it.

Bounty of the Hunt

You may exile a green card from your hand rather than pay this spell's mana cost.
Distribute three +1/+1 counters among one, two, or three target creatures. For each +1/+1 counter you put on a creature this way, remove a +1/+1 counter from that creature at the beginning of the next cleanup step.

Frostweb Spider

Reach (This creature can block creatures with flying.)
Whenever Frostweb Spider blocks a creature with flying, put a +1/+1 counter on Frostweb Spider at end of combat.

Incinerate

Incinerate deals 3 damage to any target. A creature dealt damage this way can't be regenerated this turn.

Aurochs

Trample
Whenever Aurochs attacks, it gets +1/+0 until end of turn for each other attacking Aurochs.

Woolly Mammoths

Woolly Mammoths has trample as long as you control a snow land.

Orcish Lumberjack

{T}, Sacrifice a Forest: Add three mana in any combination of {R} and/or {G}.

Deadly Insect

Shroud (This creature can't be the target of spells or abilities.)

Resize

Target creature gets +3/+3 until end of turn.
Recover {1}{G} (When a creature is put into your graveyard from the battlefield, you may pay {1}{G}. If you do, return this card from your graveyard to your hand. Otherwise, exile this card.)

Highland Weald

Highland Weald enters tapped.
{T}: Add {R} or {G}.

Stalking Yeti

When Stalking Yeti enters, if it's on the battlefield, it deals damage equal to its power to target creature an opponent controls and that creature deals damage equal to its power to Stalking Yeti.
{2}{S}: Return Stalking Yeti to its owner's hand. Activate only as a sorcery. ({S} can be paid with one mana from a snow source.)

Boreal Druid

Snow-Covered Forest

Aurochs Herd

Trample
When Aurochs Herd enters, you may search your library for an Aurochs card, reveal it, put it into your hand, then shuffle.
Whenever Aurochs Herd attacks, it gets +1/+0 until end of turn for each other attacking Aurochs.

Shape of the Wiitigo

Enchant creature
When Shape of the Wiitigo enters, put six +1/+1 counters on enchanted creature.
At the beginning of your upkeep, put a +1/+1 counter on enchanted creature if it attacked or blocked since your last upkeep. Otherwise, remove a +1/+1 counter from it.