Long-Forgotten Gohei

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

Dance of Shadows

Creatures you control get +1/+0 and gain fear until end of turn. (They can't be blocked except by artifact creatures and/or black creatures.)

Ragged Veins

Flash
Enchant creature
Whenever enchanted creature is dealt damage, its controller loses that much life.

Kodama's Reach

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Forest

Swamp

Soilshaper

Whenever you cast a Spirit or Arcane spell, target land becomes a 3/3 creature until end of turn. It's still a land.

Swallowing Plague

Swallowing Plague deals X damage to target creature and you gain X life.

Scuttling Death

Sacrifice Scuttling Death: Target creature gets -1/-1 until end of turn.
Soulshift 4 (When this creature dies, you may return target Spirit card with mana value 4 or less from your graveyard to your hand.)

Kami of the Hunt

Whenever you cast a Spirit or Arcane spell, Kami of the Hunt gets +1/+1 until end of turn.

Pull Under

Target creature gets -5/-5 until end of turn.

Gibbering Kami

Flying
Soulshift 3 (When this creature dies, you may return target Spirit card with mana value 3 or less from your graveyard to your hand.)

Devouring Greed

As an additional cost to cast this spell, you may sacrifice any number of Spirits.
Target player loses 2 life plus 2 life for each Spirit sacrificed this way. You gain that much life.

Iname, Death Aspect

When Iname, Death Aspect enters, you may search your library for any number of Spirit cards, put them into your graveyard, then shuffle.

Kodama's Might

Target creature gets +2/+2 until end of turn.
Splice onto Arcane {G} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Dripping-Tongue Zubera

When Dripping-Tongue Zubera dies, create a 1/1 colorless Spirit creature token for each Zubera that died this turn.

Burr Grafter

Sacrifice Burr Grafter: Target creature gets +2/+2 until end of turn.
Soulshift 3 (When this creature dies, you may return target Spirit card with mana value 3 or less from your graveyard to your hand.)

Wear Away

Destroy target artifact or enchantment.
Splice onto Arcane {3}{G} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Hana Kami

{1}{G}, Sacrifice Hana Kami: Return target Arcane card from your graveyard to your hand.

Venerable Kumo

Reach (This creature can block creatures with flying.)
Soulshift 4 (When this creature dies, you may return target Spirit card with mana value 4 or less from your graveyard to your hand.)

Ashen-Skin Zubera

When Ashen-Skin Zubera dies, target opponent discards a card for each Zubera that died this turn.

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.)

Kami of Lunacy

Flying
Soulshift 5 (When this creature dies, you may return target Spirit card with mana value 5 or less from your graveyard to your hand.)