Rob the Hoard

Return target artifact, enchantment, or legendary card from your graveyard to your hand. (Then exile this card. You may cast the creature later from exile.)

Crystal Dragon

Crystal Dragon // Rob the Hoard

Primevals' Glorious Rebirth

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Return all legendary permanent cards from your graveyard to the battlefield.

Arvad the Cursed

Deathtouch, lifelink
Other legendary creatures you control get +2/+2.

Blackblade Reforged

Equipped creature gets +1/+1 for each land you control.
Equip legendary creature {3}
Equip {7}

Thalia's Lancers

First strike
When Thalia's Lancers enters, you may search your library for a legendary card, reveal it, put it into your hand, then shuffle.

Benalish Honor Guard

Benalish Honor Guard gets +1/+0 for each legendary creature you control.

Hero's Heirloom

Equipped creature gets +2/+1.
As long as equipped creature is legendary, it has trample and haste.
Equip {2}

Urza's Ruinous Blast

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Exile all nonland permanents that aren't legendary.

Regent's Authority

Target creature gets +2/+2 until end of turn. If it's an enchantment creature or legendary creature, instead put a +1/+1 counter on it and it gets +1/+1 until end of turn.

Blessing of Belzenlok

Target creature gets +2/+1 until end of turn. If it's legendary, it also gains lifelink until end of turn.

Plains

Ratadrabik of Urborg

Vigilance, ward {2}
Other Zombies you control have vigilance.
Whenever another legendary creature you control dies, create a token that's a copy of that creature, except it's not legendary and it's a 2/2 black Zombie in addition to its other colors and types.

Price of Fame

This spell costs {2} less to cast if it targets a legendary creature.
Destroy target creature.
Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)