Cone of Cold 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

Roll a d20. 1—9 | Tap all creatures your opponents control. 10—19 | Tap all creatures your opponents control. Those creatures don't untap during their controllers' next untap steps. 20 | Tap all creatures your opponents control. Those creatures don't untap during their controllers' next untap steps. Until your next turn, creatures your opponents control enter tapped.

How it works : Cone of Cold

Original English text — Wizards of the Coast / Scryfall

No additional ruling has been published for this card.

Interactions with other cards

These cards' text mentions Cone of Cold.

Scion of Stygia

Flash Cone of Cold — When this creature enters, choose target creature an opponent controls, then roll a d20. 1—9 | Tap that creature. 10—20 | Tap that creature. It doesn't untap during its controller's next untap step.