Erayo within a turn

[BigMac]

Erayo, Sorotami ascendant U1
1/1
Flying
Whenever the fourth spell of a turn is played, flip Erayo, Soratami Ascendant.

When flipped
Erayo's Essence
Legendary Enchantment
Whenever an opponent plays a spell for the first time in a turn, counter that spell.

I have a couple of questions about this card.
1) You are busy with your combo deck and within your turn this card flips at your fourth spell. All spells that turn i play will be countered if i have not yet played one that turn right. This means i pretty much can play tendrills and it gets countered but all the copies still go on the stack right?
2) I played a dark ritual as 4rth spell but it is the first of the turn. Is Erayo flipped and does it counter the ritual or does the ritual trigger the erayo on resolution.
3) same as in 2) but now my opponent tries to FoW my ritual. I can counter his FoW but by now the erayo is flipped before resolution of my ritual. Will it be countered by erayo even though i cast it before it was flipped?
4) When you play erayo, does it start counting spells from tha point on or are all spells allready played that turn still counted. (for example, i play land, mox erayo, lotus necropotence which is the fourth spell, does erayo flip? In other words, does erayo itself count towards the number of spells or does the counting start as soon as erayo is in play?
5) same as in 4), if necropotence is the fourth spell and erayo is turned upon necropotence on the stack as being the fourth spell, will the FoW my opponent tries to play be countered by the enchantment when it is the first spell of called FoW my opponent plays that turn.

Hope anybody knows how to do this.

[Jacob Orlove]

Erayo only counters the first spell you play in a turn. It will never counter more than one card.

1) You are busy with your combo deck and within your turn this card flips at your fourth spell. All spells that turn i play will be countered if i have not yet played one that turn right. This means i pretty much can play tendrills and it gets countered but all the copies still go on the stack right?

Wrong. Erayo counters your first spell in a turn, and you played that first spell well before you played your fourth. Nothing will get countered that turn.
2) Erayo has to already be flipped for the "counter the first spell" to trigger. If Ritual is the fourth spell of the turn, Erayo will flip, but even if it is your first spell, it is not countered.
3) Same as 2. Erayo has to be flipped when you play the spell, not when it resolves.
4) It's like storm--it counts from the first spell of the turn. If you play Erayo as the fourth spell in a turn, though, it will not flip, because it is not in play to trigger.
5) Necro is played, Erayo triggers. If they let Erayo's trigger resolve, Erayo will flip and then counter the Force (if it's their first card of the turn). If they Force immediately, Erayo's flip is still on the stack, and the Force will resolve first.

[BigMac]

so it basically is the first spell of an opponent. And not a certain spell for the first time.

as i read it it counters every spell they play for the first time, but i guess that is wrong.

[Jacob Orlove]

The errata just turns the printed text into a triggered ability.

As printed, Erayo's Essence reads:
"Counter the first spell played by each opponent each turn".

That's basically what the card is supposed to do. The errata is slightly confusing, but only because it's hard to make that into a triggered ability.

[BigMac]

and another idea turns to dust.

Ye can close this if ye want.