AI DraftFeb 26, 2026
Cloud Key + Mystic Forge + Sensei's Divining Top
Overview
With Cloud Key set to artifact, it reduces the generic mana portion of artifact spells you cast by 
(Ruling [2021-03-19]). Mystic Forge lets you look at the top card and cast artifact (and colorless) spells from the top of your library; casting such a card from the top is still casting a spell and follows the normal casting steps and library/top visibility rules . Sensei's Divining Top can reorder the top of your library () or draw and put itself on top (
); the two Top abilities can be used in sequence (Ruling [2016-06-08]) to influence what Mystic Forge sees. The end result: if Cloud Key chose artifact and the top card is an artifact spell, you may cast it from the top using Mystic Forge, and Cloud Key’s reduction applies to the generic portion when determining the spell’s total cost (only generic mana is reduced, Ruling [2021-03-19]).
(Ruling [2021-03-19]). Mystic Forge lets you look at the top card and cast artifact (and colorless) spells from the top of your library; casting such a card from the top is still casting a spell and follows the normal casting steps and library/top visibility rules . Sensei's Divining Top can reorder the top of your library () or draw and put itself on top (); the two Top abilities can be used in sequence (Ruling [2016-06-08]) to influence what Mystic Forge sees. The end result: if Cloud Key chose artifact and the top card is an artifact spell, you may cast it from the top using Mystic Forge, and Cloud Key’s reduction applies to the generic portion when determining the spell’s total cost (only generic mana is reduced, Ruling [2021-03-19]).Step 1
Ensure Cloud Key entered naming "artifact." That makes artifact spells you cast cost less in their generic portion (Ruling [2021-03-19]).
less in their generic portion (Ruling [2021-03-19]).Step 2
Use Mystic Forge's passive line ("You may look at the top card of your library. You may cast artifact spells and colorless spells from the top of your library.") to look at the top card and, if it's an artifact spell you want, choose to cast it; casting from the top is still casting a spell and follows the normal casting steps and the top-card visibility rules .
Step 3
When you begin to cast that top-card artifact spell, follow the casting steps in . Announce the spell and move it to the stack . Determine the spell’s total cost ; at this time Cloud Key’s reduction applies to the generic portion of that total cost (Ruling [2021-03-19]).
Step 4
Activate mana abilities and pay the determined (locked-in) total cost [601.2f–g]. The spell becomes cast once the casting steps complete . Note that casting-cost changes after this point don’t affect that already-locked-in cost .
Step 5
If you need the top card to be an artifact before you cast, use Sensei’s Divining Top’s ability to look at and reorder the top three cards or use its draw ability to change the top; the Top’s abilities can be sequenced as allowed by the ruling so you can draw and then reorder ( and Ruling [2016-06-08]).
ability to look at and reorder the top three cards or use its draw ability to change the top; the Top’s abilities can be sequenced as allowed by the ruling so you can draw and then reorder ( and Ruling [2016-06-08]).Step 6
Be aware that if the top card changes while you are in the middle of casting a spell, the new top won’t be revealable or inspectable until the spell finishes becoming cast .
Resolution
If Cloud Key’s chosen type is artifact, it reduces the generic portion of an artifact spell’s total cost by when you cast that spell from the top of your library with Mystic Forge; casting from the top follows the normal casting rules and the cost reduction is applied when the total cost is determined . You can use Sensei’s Divining Top to examine or change the top cards so Mystic Forge sees (and permits you to cast) an artifact spell; you may also sequence the Top’s abilities as allowed by the ruling (Ruling [2016-06-08]). If the top card changes while a spell is being cast, the new top card can’t be looked at until the spell becomes cast .
when you cast that spell from the top of your library with Mystic Forge; casting from the top follows the normal casting rules and the cost reduction is applied when the total cost is determined . You can use Sensei’s Divining Top to examine or change the top cards so Mystic Forge sees (and permits you to cast) an artifact spell; you may also sequence the Top’s abilities as allowed by the ruling (Ruling [2016-06-08]). If the top card changes while a spell is being cast, the new top card can’t be looked at until the spell becomes cast .Feedback