Rhonas's Monument
Legendary Artifact
Green creature spells you cast cost 
less to cast.
Whenever you cast a creature spell, target creature you control gets +2/+2 and gains trample until end of turn.
"The worthy shall hone a strong body to endure the boundless energies of the afterlife." —Monument inscription
イラスト：
Amonkhet#236アンコモン英語適正
裁定
The triggered ability of Rhonas’s Monument can’t target the creature spell that caused it to trigger.
Each Monument has one ability that reduces the cost of creature spells of a certain color, and a triggered ability that triggers whenever you cast any creature spell—not just a creature spell of that color.
A creature spell that’s multiple colors is each of those colors. For example, Ahn-Crop Champion is a white creature and a green creature, so it can benefit from either Oketra’s Monument or Rhonas’s Monument—or both at once.
To determine the total cost of a creature spell, start with the mana cost or alternative cost you’re paying, add any cost increases, then apply any cost reductions. The converted mana cost of the creature remains unchanged, no matter what the total cost to cast it was.
Each Monument’s triggered ability triggers as the creature spell is cast and resolves before that creature spell resolves. The ability will resolve even if that creature spell is countered.