Garenbrig Squire

Whenever you cast a creature spell that has an Adventure, Garenbrig Squire gets +1/+1 until end of turn. (It doesn't need to have gone on the adventure first.)

Undermountain Adventurer

Vigilance
When Undermountain Adventurer enters, you take the initiative.
{T}: Add {G}{G}. If you've completed a dungeon, add six {G} instead.

Edgewall Innkeeper

Whenever you cast a creature spell that has an Adventure, draw a card. (It doesn't need to have gone on the adventure first.)

Gorion, Wise Mentor

Vigilance
Whenever you cast an Adventure spell, you may copy it. You may choose new targets for the copy.

Wandermare

Whenever you cast a creature spell that has an Adventure, put a +1/+1 counter on Wandermare. (It doesn't need to have gone on the adventure first.)

Lucky Clover

Whenever you cast an Adventure instant or sorcery spell, copy it. You may choose new targets for the copy.

Mysterious Pathlighter

Flying
Each creature you control that has an Adventure enters with an additional +1/+1 counter on it. (It doesn't need to have gone on the adventure first.)