Gríma, Saruman's Footman — ruling 1

If the spell you cast has {X} in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.

Gríma, Saruman's Footman — ruling 2

If you choose not to cast the card, it is put on the bottom of its owner's library in a random order along with the other exiled cards.

Gríma, Saruman's Footman — ruling 3

If you cast a spell "without paying its mana cost," you can't pay any alternative costs. You can, however, pay additional costs, such as kicker costs. If the card has any mandatory additional costs, you must pay those.

Gríma, Saruman's Footman — ruling 4

The cards are exiled face up. All players will be able to see them.

Gríma, Saruman's Footman — ruling 5

If that player exiles their entire library without exiling an instant or sorcery card, they will randomize the order of the exiled cards, and the cards then become that player's library, ending the effect. They will not continue to exile and randomize their library forever.

Gríma, Saruman's Footman — ruling 6

You cast the card while the ability is resolving and still on the stack. You can't wait to cast it later in the turn.

Gríma, Saruman's Footman : règles, fonctionnement et interactions (MTG)

Gríma, Saruman's Footman is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Gríma can't be blocked. Whenever Gríma deals combat damage to a player, that player exiles cards from the top of their library until they exile an instant or sorcery card. You may cast that card without paying its mana cost. Then that player puts the exiled cards that weren't cast this way on the bottom of their library in a random order.

How it works : Gríma, Saruman's Footman

Original English text — Wizards of the Coast / Scryfall

#1June 16, 2023· Wizards of the Coast
If the spell you cast has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
No other card is named in this ruling.
#2June 16, 2023· Wizards of the Coast
If you choose not to cast the card, it is put on the bottom of its owner's library in a random order along with the other exiled cards.
No other card is named in this ruling.
#3June 16, 2023· Wizards of the Coast
If you cast a spell "without paying its mana cost," you can't pay any alternative costs. You can, however, pay additional costs, such as kicker costs. If the card has any mandatory additional costs, you must pay those.
No other card is named in this ruling.
#4June 16, 2023· Wizards of the Coast
The cards are exiled face up. All players will be able to see them.
No other card is named in this ruling.
#5June 16, 2023· Wizards of the Coast
If that player exiles their entire library without exiling an instant or sorcery card, they will randomize the order of the exiled cards, and the cards then become that player's library, ending the effect. They will not continue to exile and randomize their library forever.
No other card is named in this ruling.
#6June 16, 2023· Wizards of the Coast
You cast the card while the ability is resolving and still on the stack. You can't wait to cast it later in the turn.
No other card is named in this ruling.