Rules FAQ
The timing charts on pg 25 of the RRG show that there is no opportunity for player actions until AFTER dominance is awarded. So The Tickler will be standing and count his strength towards dominance, then kneel to trigger to his effect.
Ally.
Dominance Action: Kneel The Tickler to discard the top card of an opponent's deck. Then, you may choose 1 copy of that card, and discard it from play.
Link: Decklists
Rules FAQ
The timing charts on pg 25 of the RRG show that there is no opportunity for player actions until AFTER dominance is awarded. So The Tickler will be standing and count his strength towards dominance, then kneel to trigger to his effect.