If you want to activate the activated ability of Teysa, Orzhov Scion, does "sacrifice 3 creatures" count as 1 cost, or 3 separate costs? And, does it matter which it is at all? 601.2g says
The player pays the total cost in any order. Does this mean that the creatures are sacrificed in any order; or are they sacrificed all at the same time, as 1 cost?
Further, is it any different if they are sacrificed all at the same time, or one after the other? I believe it wouldn't matter, because no triggered abilities would go on the stack until a player is about to receive priority anyway. 603.6d says
...will trigger based on their existence, and the appearance of objects, prior to the event rather than afterward. But what is "the event" that it looks prior to? Is each sacrifice of a creature a separate event? If this were the case, then sacrificing Teysa before the other creatures would mean that you don't get the tokens for Teysa's triggered ability. Or, is "the event" the activating of Teysa's ability, in which case the order makes no difference?