In multi players game, more than one players control Notion Thief. If a player try to draw his/her second card is/her second card, each replacement effect only affect once and result in only one player who control Notion Thief draw a card according to FAQ.
I think it is from
614.5. A replacement effect doesn’t invoke itself repeatedly; it gets only one opportunity to affect an event or any modified events that may replace it.
But why cannot we explain that with
104.4f In a multiplayer game using the limited range of influence option, if the game somehow enters a “loop” of mandatory actions, repeating a sequence of events with no way to stop, the game is a draw for each player who controls an object that’s involved in that loop, as well as for each player within the range of influence of any of those players. Only those players leave the game; the game continues for all other players.
to make the situation become a “loop” then draw game?

Could you give me a good example to explain 104.4f and the difference with 614.5?

Edited Che Wei Sung (Feb. 13, 2018 08:02:55 PM)

I'm not entirely sure on the specific question you're asking here, so I'm going to start by explaining in broad terms why 614.5 exists, and continue from there.

In short, 614.5 exists because it has to. If a replacement effect could invoke itself repeatedly, many, many cards would grind the game to an immediate halt, because they use replacement effects that replace one thing with something that would otherwise invoke their own effect again. There's a ton of cards like this, but the one that comes to mind first for me is Furnace of Rath, which replaces damage with a larger amount of damage instead. If Furnace of Rath could apply to the same event multiple times, as soon as anything attempted to deal damage, the Furnace would trap the game in an infinite loop where the Furnace doubles the incoming damage, then doubles it again (because it's still damage), then doubles it again, then doubles it again over and over forever–the game would never get to the point where that damage actually gets dealt because it's too busy doubling it.

We do know what happens in situations where the game gets stuck endlessly repeating itself: 104.4b steps in and causes the game to end in a draw. (Or, for multiplayer games that use range of influence, 104.4f steps in and removes every player involved.) But is that what we want to happen? Does it make any sense for Furnace of Rath to effectively read “{1}{R}{R}{R}: The game is a draw as soon as anything attempts to deal damage to a creature or player”? No. This obviously isn't what the card should do; the very idea is ridiculous. Thus, we have 614.5 to stop that from happening. It avoids this kind of infinite self-replacement loop by stopping replacement effects from re-applying to events they've already applied to, and it does so even if some other effect later modifies the event further. (Because we don't want two Furnace of Raths making the game grind to a halt any more than we wanted one of them doing it.) This is where the ruling you mentioned in the FAQ comes from–the ability from each Notion Thief can be applied once and only once, and the last Thief to be applied wins out, whichever one that happens to be.

Edited Callum Milne (Feb. 17, 2018 01:56:54 PM)