703.1e At any time during the above steps, if the player is unable to finish playing the ability, the entire
process is rewound and the game state reverts to the state before playing the ability was attempted.
703.1f After the above steps are completed, that ability becomes played, and the following happens in order.
703.1h A window opens for reacts that can be played “only when an enemy plays an ability” and, in the case
of an attack ability (600), reacts that can be played “only when an attack targets [a character]”, “only
when [a character] is targeted by an attack.”, or “if [a character] is in the affected area of an enemy
AOE attack.”
If a react played during this window negates that ability, that ability does nothing more and its costs are not refunded.
It is a tricky thing.
Normally, cause the window for counterspell opens later than 703.1f the ability should count as played.
But the little phrase "Negate that ability" is what makes it tricky.
But it only says "If a react played during this window negates that ability, that ability does nothing more and its costs are not refunded."
So it is not rewoundded like there where problems before step 703.1f, it just "does nothing more".
So it still counts as played and VK may use his ability to revive his pet.