Timing / Impulse question regarding "Temptation"

Temptation
Action. Serpentis. 1 Blood

Put this card on a ready vampire; you still control this card. During your master phase, you may put a counter on this card. During your minion phase, if the number of counters on this card equals or exceeds the amount of blood on this vampire, you may burn the counters to untap this vampire and take control of him or her until the end of the turn.
As above, and add a counter when you play this card.

I know, that I can take control of a vampire with enough counters during my minion phase, even if it is during an action of one of my minions and the specific vampire is attempting to block, which results in cancelling the block.

Following situation:
My vampire A takes an action with 0 stealth und the vampire B (with enough temptation counters) attempts to block.

Question:
Can vampire A play an action modifier for stealth (to cycle a card) AND can I (afterwards) immediately take control of vampire B, OR do I have to give the controller of B the chance to play (and cycle) reaction cards?

Thanks in advance!