Hikari, Twilight Guardian

Flying
Whenever you cast a Spirit or Arcane spell, you may exile Hikari, Twilight Guardian. If you do, return it to the battlefield under its owner's control at the beginning of the next end step.

Obscura Ascendancy

Whenever you cast a spell, if its mana value is equal to 1 plus the number of soul counters on Obscura Ascendancy, put a soul counter on Obscura Ascendancy, then create a 2/2 white Spirit creature token with flying.
As long as there are five or more soul counters on Obscura Ascendancy, Spirits you control get +3/+3.

Sire of the Storm

Flying
Whenever you cast a Spirit or Arcane spell, you may draw a card.

Thief of Hope

Whenever you cast a Spirit or Arcane spell, target opponent loses 1 life and you gain 1 life.
Soulshift 2 (When this creature dies, you may return target Spirit card with mana value 2 or less from your graveyard to your hand.)

Long-Forgotten Gohei

Arcane spells you cast cost {1} less to cast.
Spirit creatures you control get +1/+1.

Ore Gorger

Whenever you cast a Spirit or Arcane spell, you may destroy target nonbasic land.

Drogskol Captain

Flying
Other Spirit creatures you control get +1/+1 and have hexproof. (They can't be the targets of spells or abilities your opponents control.)

Loam Dweller

Whenever you cast a Spirit or Arcane spell, you may put a land card from your hand onto the battlefield tapped.

Battleground Geist

Flying
Other Spirit creatures you control get +1/+0.

Briarknit Kami

Whenever you cast a Spirit or Arcane spell, put a +1/+1 counter on target creature.

Soul of Magma

Whenever you cast a Spirit or Arcane spell, Soul of Magma deals 1 damage to target creature.

Kodama of the South Tree

Whenever you cast a Spirit or Arcane spell, each other creature you control gets +1/+1 and gains trample until end of turn.

Oyobi, Who Split the Heavens

Flying
Whenever you cast a Spirit or Arcane spell, create a 3/3 white Spirit creature token with flying.

Bounteous Kirin

Flying
Whenever you cast a Spirit or Arcane spell, you may gain life equal to that spell's mana value.

Yuki-Onna

When Yuki-Onna enters, destroy target artifact.
Whenever you cast a Spirit or Arcane spell, you may return Yuki-Onna to its owner's hand.

Elder Pine of Jukai

Whenever you cast a Spirit or Arcane spell, reveal the top three cards of your library. Put all land cards revealed this way into your hand and the rest on the bottom of your library in any order.
Soulshift 2 (When this creature dies, you may return target Spirit card with mana value 2 or less from your graveyard to your hand.)

Petalmane Baku

Whenever you cast a Spirit or Arcane spell, you may put a ki counter on Petalmane Baku.
{1}, Remove X ki counters from Petalmane Baku: Add X mana of any one color.

Baku Altar

Whenever you cast a Spirit or Arcane spell, you may put a ki counter on Baku Altar.
{2}, {T}, Remove a ki counter from Baku Altar: Create a 1/1 colorless Spirit creature token.

Celestial Kirin

Flying
Whenever you cast a Spirit or Arcane spell, destroy all permanents with that spell's mana value.

Kami of the Waning Moon

Flying
Whenever you cast a Spirit or Arcane spell, target creature gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)

Kyodai, Soul of Kamigawa

Flash
Flying
When Kyodai, Soul of Kamigawa enters, another target permanent gains indestructible for as long as you control Kyodai.
{W}{U}{B}{R}{G}: Kyodai gets +5/+5 until end of turn.

Abzan Ascendancy

When Abzan Ascendancy enters, put a +1/+1 counter on each creature you control.
Whenever a nontoken creature you control dies, create a 1/1 white Spirit creature token with flying.

Spectral Arcanist

Flying
When Spectral Arcanist enters, you may cast an instant or sorcery spell with mana value less than or equal to the number of Spirits you control from a graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.

Rattlechains

Flash
Flying
When Rattlechains enters, target Spirit gains hexproof until end of turn.
You may cast Spirit spells as though they had flash.

Infernal Kirin

Flying
Whenever you cast a Spirit or Arcane spell, target player reveals their hand and discards all cards with that spell's mana value.

Skyfire Kirin

Flying
Whenever you cast a Spirit or Arcane spell, you may gain control of target creature with that spell's mana value until end of turn.

Guardian of Solitude

Whenever you cast a Spirit or Arcane spell, target creature gains flying until end of turn.

Cloudhoof Kirin

Flying
Whenever you cast a Spirit or Arcane spell, you may have target player mill X cards, where X is that spell's mana value.

Nikko-Onna

When Nikko-Onna enters, destroy target enchantment.
Whenever you cast a Spirit or Arcane spell, you may return Nikko-Onna to its owner's hand.

Blood Age General

{T}: Attacking Spirits get +1/+0 until end of turn.

Kyoki, Sanity's Eclipse

Whenever you cast a Spirit or Arcane spell, target opponent exiles a card from their hand.