Ignoble Hierarch

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
{T}: Add {B}, {R}, or {G}.

Order of Sacred Dusk

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Flying, lifelink, haste
Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
Other Vampires you control have exalted.

Giltspire Avenger

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
{T}: Destroy target creature that dealt damage to you this turn.

Cathedral of War

This land enters tapped.
Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
{T}: Add {C}.

Noble Hierarch

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
{T}: Add {G}, {W}, or {U}.

Raiyuu, Storm's Edge

First strike
Whenever a Samurai or Warrior you control attacks alone, untap it. If it's the first combat phase of the turn, there is an additional combat phase after this phase.

Battlegrace Angel

Flying
Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)
Whenever a creature you control attacks alone, it gains lifelink until end of turn.

Idolized

Enchant creature
Enchanted creature has "Whenever this creature attacks alone, it gets +X/+X until end of turn, where X is the number of nonland permanents you control."

Bilbo's Ring

During your turn, equipped creature has hexproof and can't be blocked.
Whenever equipped creature attacks alone, you draw a card and you lose 1 life.
Equip Halfling {1} ({1}: Attach to target Halfling you control. Equip only as a sorcery.)
Equip {4} ({4}: Attach to target creature you control. Equip only as a sorcery.)