Grip of the Roil — ruling 1

Grip of the Roil can target a creature that's already tapped. It still won't untap during its controller's next untap step.

Grip of the Roil — ruling 2

Grip of the Roil tracks the creature, but not its controller. If the creature changes controllers before its first controller's next untap step has come around, then it won't untap during its new controller's next untap step.

Grip of the Roil — ruling 3

For some cards, surge represents only an alternative cost, a discount that applies if you or a teammate has cast another spell this turn. Other cards, like Reckless Bushwhacker, have additional abilities or effects if you paid the surge cost to cast the spell.

Grip of the Roil — ruling 4

The other spell that you or a teammate cast can be one that's resolved, one that was countered, or (for instants with surge) one that's still on the stack.

Grip of the Roil — ruling 5

If an instant or sorcery spell cast for its surge cost is copied, the copy is also considered to have had its surge cost paid.

Grip of the Roil — ruling 6

Casting a spell for its surge cost doesn't change its mana cost or its mana value.

Grip of the Roil : règles, fonctionnement et interactions (MTG)

Grip of the Roil 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

Surge (You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.) Tap target creature. It doesn't untap during its controller's next untap step. Draw a card.

How it works : Grip of the Roil

Original English text — Wizards of the Coast / Scryfall

#1January 22, 2016· Wizards of the Coast
Grip of the Roil can target a creature that's already tapped. It still won't untap during its controller's next untap step.
No other card is named in this ruling.
#2January 22, 2016· Wizards of the Coast
Grip of the Roil tracks the creature, but not its controller. If the creature changes controllers before its first controller's next untap step has come around, then it won't untap during its new controller's next untap step.
No other card is named in this ruling.
#3January 22, 2016· Wizards of the Coast
For some cards, surge represents only an alternative cost, a discount that applies if you or a teammate has cast another spell this turn. Other cards, like Reckless Bushwhacker, have additional abilities or effects if you paid the surge cost to cast the spell.
No other card is named in this ruling.
#4January 22, 2016· Wizards of the Coast
The other spell that you or a teammate cast can be one that's resolved, one that was countered, or (for instants with surge) one that's still on the stack.
No other card is named in this ruling.
#5January 22, 2016· Wizards of the Coast
If an instant or sorcery spell cast for its surge cost is copied, the copy is also considered to have had its surge cost paid.
No other card is named in this ruling.
#6January 22, 2016· Wizards of the Coast
Casting a spell for its surge cost doesn't change its mana cost or its mana value.
No other card is named in this ruling.