No, participant C will hold controlling it.
Each spells have steady results which modify the creature’s traits in Layer 2, and the one with the newest timestamp wins. It does not matter that Act of Treason is simply momentary (and one may say Donate does not have a period in any respect):
611.2a A steady impact generated by the decision of a spell or potential lasts so long as acknowledged by the spell or potential creating it (equivalent to “till finish of flip”). If no period is acknowledged, it lasts till the top of the sport.
Related components of the layer system:
613.1b Layer 2: Management-changing results are utilized.
613.3. Inside layers 2–6, apply results from characteristic-defining talents first (see rule 604.3), then all different results in timestamp order (see rule 613.7). Notice that dependency could alter the order by which results are utilized inside a layer. (See rule 613.8.)
The scenario would have been completely different if Act of Treason had learn one thing like
Acquire management of goal creature. On the finish of flip, return it to it is proprietor’s management.
as a result of then that final half can be ‘later’ than, and overriding the impact of, your Donate.
A associated instance: you forged Donate on one among your creatures and provides it to Participant C. Participant A casts Act of Treason so it comes underneath Participant A’s management; on the finish of flip, it is returned to Participant C, to not you.
