Arni Slays the Troll

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Target creature you control fights up to one target creature you don't control.
II — Add {R}. Put two +1/+1 counters on up to one target creature you control.
III — You gain life equal to the greatest power among creatures you control.

Mirror Box

The "legend rule" doesn't apply to permanents you control.
Each legendary creature you control gets +1/+1.
Each nontoken creature you control gets +1/+1 for each other creature you control with the same name as that creature.

Garruk's Uprising

When Garruk's Uprising enters the battlefield, if you control a creature with power 4 or greater, draw a card.
Creatures you control have trample. (They can deal excess combat damage to the player or planeswalker they're attacking.)
Whenever a creature with power 4 or greater enters the battlefield under your control, draw a card.

Ruby, Daring Tracker

Haste
Whenever Ruby, Daring Tracker attacks while you control a creature with power 4 or greater, Ruby gets +2/+2 until end of turn.
{T}: Add {R} or {G}.

Have

Ruric Thar, the Unbowed

Vigilance, reach
Ruric Thar, the Unbowed attacks each combat if able.
Whenever a player casts a noncreature spell, Ruric Thar deals 6 damage to that player.

Ulrich, Uncontested Alpha

Whenever this creature transforms into Ulrich, Uncontested Alpha, you may have it fight target non-Werewolf creature you don't control.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform Ulrich, Uncontested Alpha.

Ulrich of the Krallenhorde

Whenever this creature enters the battlefield or transforms into Ulrich of the Krallenhorde, target creature gets +4/+4 until end of turn.
At the beginning of each upkeep, if no spells were cast last turn, transform Ulrich of the Krallenhorde.

Ulrich of the Krallenhorde // Ulrich, Uncontested Alpha

Xenagos, God of Revels

Indestructible
As long as your devotion to red and green is less than seven, Xenagos isn't a creature.
At the beginning of combat on your turn, another target creature you control gains haste and gets +X/+X until end of turn, where X is that creature's power.

Forest

Samut, Tyrant Smasher

Creatures you control have haste.
−1: Target creature gets +2/+1 and gains haste until end of turn. Scry 1.

Doors of Durin

Whenever you attack, scry 2, then you may reveal the top card of your library. If it's a creature card, put it onto the battlefield tapped and attacking. Until your next turn, it gains trample if you control a Dwarf and hexproof if you control an Elf.

Anzrag, the Quake-Mole

Whenever Anzrag, the Quake-Mole becomes blocked, untap each creature you control. After this phase, there is an additional combat phase.
{3}{R}{R}{G}{G}: Anzrag must be blocked each combat this turn if able.

Bard Class

(Gain the next level as a sorcery to add its ability.)
Legendary creatures you control enter the battlefield with an additional +1/+1 counter on them.
{R}{G}: Level 2
Legendary spells you cast cost {R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
{3}{R}{G}: Level 3
Whenever you cast a legendary spell, exile the top two cards of your library. You may play them this turn.

Samut, Voice of Dissent

Flash
Double strike, vigilance, haste
Other creatures you control have haste.
{W}, {T}: Untap another target creature.

Domri, Anarch of Bolas

Creatures you control get +1/+0.
+1: Add {R} or {G}. Creature spells you cast this turn can't be countered.
−2: Target creature you control fights target creature you don't control.

Hajar, Loyal Bodyguard

Sacrifice Hajar, Loyal Bodyguard: Legendary creatures you control get +1/+0 and gain indestructible until end of turn.

Domri, Chaos Bringer

+1: Add {R} or {G}. If that mana is spent on a creature spell, it gains riot. (It enters the battlefield with your choice of a +1/+1 counter or haste.)
−3: Look at the top four cards of your library. You may reveal up to two creature cards from among them and put them into your hand. Put the rest on the bottom of your library in a random order.
−8: You get an emblem with "At the beginning of each end step, create a 4/4 red and green Beast creature token with trample."

Rockfall Vale

Rockfall Vale enters the battlefield tapped unless you control two or more other lands.
{T}: Add {R} or {G}.

Prey Upon

Target creature you control fights target creature you don't control. (Each deals damage equal to its power to the other.)

Mountain

Domri's Ambush

Put a +1/+1 counter on target creature you control. Then that creature deals damage equal to its power to target creature or planeswalker you don't control.

Halana and Alena, Partners

First strike, reach
At the beginning of combat on your turn, put X +1/+1 counters on another target creature you control, where X is Halana and Alena's power. That creature gains haste until end of turn.