Rin and Seri, Inseparable

Whenever you cast a Dog spell, create a 1/1 green Cat creature token.
Whenever you cast a Cat spell, create a 1/1 white Dog creature token.
{R}{G}{W}, {T}: Rin and Seri deals damage to any target equal to the number of Dogs you control. You gain life equal to the number of Cats you control.

Bottle Gnomes

Sacrifice this creature: You gain 3 life.

Comet, Stellar Pup

0: Roll a six-sided die.
1 or 2 — [+2], then create two 1/1 green Squirrel creature tokens. They gain haste until end of turn.
3 — [−1], then return a card with mana value 2 or less from your graveyard to your hand.
4 or 5 — Comet deals damage equal to the number of loyalty counters on him to a creature or player, then [−2].
6 — [+1], and you may activate Comet's loyalty ability two more times this turn.

Infernal Spawn of Evil

Flying, first strike
{1}{B}, Reveal this card from your hand, Say "It's coming": This card deals 1 damage to target opponent or planeswalker. Activate only during your upkeep and only once each turn.

Jodah, Archmage Eternal

Flying
You may pay {W}{U}{B}{R}{G} rather than pay the mana cost for spells you cast.

Infernal Spawn of Infernal Spawn of Evil

Flying, first strike, trample
Once each turn, while you're searching your library, you may pay {1}{B}, reveal this card from your library and say "I'm coming, too" If you do, this card deals 2 damage to a player of your choice.