Henge Walker
Artifact Creature — Golem
Adamant — If at least three mana of the same color was spent to cast this spell, this creature enters with a +1/+1 counter on it.
Everything that inhabits Garenbrig is affected by the wild magic flowing through the Great Henge.
Titus Lunter
Throne of Eldraine (ELD)
• #221Rulings
If an effect allows you to cast a spell without paying its mana cost, you can't choose to cast it and pay unless another rule or effect allows you to cast that spell for a cost. Similarly, you can't waive a cost reduction unless that effect says you may.
(wotc • 2019-10-04)
Adamant effects check what mana was actually spent to cast a spell. If an effect allows you to spend mana “as though it were mana” of any color or type, that allows you to spend mana you couldn't otherwise spend, but it doesn't change what mana you spent to cast the spell.
(wotc • 2019-10-04)
If you copy a spell that has an adamant ability, no mana was spent to cast the copy at all, so that ability won't apply.
(wotc • 2019-10-04)
Rulings
If an effect allows you to cast a spell without paying its mana cost, you can't choose to cast it and pay unless another rule or effect allows you to cast that spell for a cost. Similarly, you can't waive a cost reduction unless that effect says you may.
(wotc • 2019-10-04)
Adamant effects check what mana was actually spent to cast a spell. If an effect allows you to spend mana “as though it were mana” of any color or type, that allows you to spend mana you couldn't otherwise spend, but it doesn't change what mana you spent to cast the spell.
(wotc • 2019-10-04)
If you copy a spell that has an adamant ability, no mana was spent to cast the copy at all, so that ability won't apply.
(wotc • 2019-10-04)