Extra turns (Stacking the turns)

[Offler]

There are few very rare permanents which can grant an extra turn, however they also can give extra turn to the opponent

Magosi, the Waterveil and Wormfang Manta.

I want to confirm something i have heard about stacking of such effects.

There is one untapped Magosi, the Waterveil in play.
I will activate its ability and put an Eon counter on it.
Then i will untap the land by Fatestitcher.
Tap Magosi, the Waterveil again to remove the counter and return the land on my hand.

Who will have next turn?

If it works like it was described to be its similar like with stacking (last in, first out) so the next turn wil be mine again, so I can play the Magosi, the Waterveil again, possibly untap it, and then repeat the process.

This will give to my opponent possibly unlimited numbers of turns, however I will be always able to stack another turn on top...

(to be honest this is the most crazy thing i have ever heard)

[cdr]

500.7. Some effects can give a player extra turns. They do this by adding the turns directly after the current turn. If a player gets multiple extra turns or if multiple players get extra turns during a single turn, the extra turns are added one at a time. The most recently created turn will be taken first.

Magosi's first ability creates an effect that will skip the next turn you get. If you activate the second ability, the next turn you get will be the extra turn, for a net effect of accomplishing nothing but returning Magosi to your hand.

[Offler]

I see. the effect will be negated.

However last abillity still works multiple times with Rings of Brighthearth.

[AngryTroll]

What happens if you cast an Emrakul, the Aeons Torn during the extra turns after time has run out?

Examples: Say you have the second and fourth extra turns, and you hardcast Emrakul on extra turn four. Do you get turn 5? Does your opponent get another turn?

What if you cast him on turn 5 of extra turns? Thanks.

[cdr]

In extra turns, there are five turns period. One player could take most, all or none of those turns if extra turn or turn-skipping effects are involved.