I think that this is a legal play, I just want confirmation before I incorrectly trigger this:

Play Dothraki Vanguard. Search and find Braided Screamers. Put Screamers into play, then trigger Screamers from playing Vanguard.

Ok. This was answered on AGOTcards. You can indeed trigger the Screamers in this way.

This has already been asked and answered with Pale Steel Link and whatever response chain you put into play with it.

Is that means it 100% valid?

Could someone help explain the mechanism logic?

Tks

The response opportunity of "playing a Dothraki character with cost at least 3" stays open throughout the response step.

What if I use the effect of Dothraki Vanguard to put into play another Dothraki Vanguard?

Could I trigger the effect once more from the just played card?

Tks

The answer is no, you have to play it from your hand for it to trigger.

EDIT

I see what you are getting at, you want to trigger the Second Vanguard against the First Vanguard being played. I am not so certain on this.

What if I use the effect of Dothraki Vanguard to put into play another Dothraki Vanguard?

Could I trigger the effect once more from the just played card?

Tks

You cannot. The Dothraki Vanguard's ability is self-referential and can only be triggered off itself entering play. Any other copy of the DV cannot trigger off of other copies of DV entering play.

I was sick of typing the whole name.

Thanks all ^^