Frostfist Strider
Creature — Elemental Giant
Ward 
(Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays .)
When this creature enters, tap target creature an opponent controls and put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Francisco Miyara
Dominaria United (DMU)
• #51Rulings
You may choose a creature that is already tapped as the target of Frostfist Strider’s last ability.
(wotc • 2022-09-09)
If a permanent has more than one stun counter on it, only one will be removed each time it would become untapped.
(wotc • 2022-09-09)
Abilities that trigger when a permanent “becomes untapped” won’t trigger if a stun counter is removed instead.
(wotc • 2022-09-09)
If a tapped permanent with a stun counter on it would become untapped, a stun counter will be removed from it instead. This is a replacement effect.
(wotc • 2022-09-09)
Stun counters replace untapping for any reason, including players untapping tapped permanents during their untap steps.
(wotc • 2022-09-09)
If untapping a permanent is part of a cost (such as that of Halo Fountain’s first ability), you may pay that cost by “untapping” a tapped permanent with a stun counter on it. The stun counter will be removed and the creature will remain tapped. However, the cost will still be paid.
(wotc • 2022-09-09)
Rulings
You may choose a creature that is already tapped as the target of Frostfist Strider’s last ability.
(wotc • 2022-09-09)
If a permanent has more than one stun counter on it, only one will be removed each time it would become untapped.
(wotc • 2022-09-09)
Abilities that trigger when a permanent “becomes untapped” won’t trigger if a stun counter is removed instead.
(wotc • 2022-09-09)
If a tapped permanent with a stun counter on it would become untapped, a stun counter will be removed from it instead. This is a replacement effect.
(wotc • 2022-09-09)
Stun counters replace untapping for any reason, including players untapping tapped permanents during their untap steps.
(wotc • 2022-09-09)
If untapping a permanent is part of a cost (such as that of Halo Fountain’s first ability), you may pay that cost by “untapping” a tapped permanent with a stun counter on it. The stun counter will be removed and the creature will remain tapped. However, the cost will still be paid.
(wotc • 2022-09-09)