Hello! I'm pretty sure about the answers to these questions, but just wanted to be 100% about them, so I thought I'd come to you:

1 - If I have a Wildling Horde and 3 The North Agendas, can I drop the Wildling Horde in the Setup Phase as a 4-cost character?

2 - What if one of the Agendas is Blood of the First Men, which reduces the first Wildling you play by 2? Can I drop a Wildling with it's cost -2 (for example, Craster for free)?

3 - Now, a more complicated question: if I have an any phase effect that states "target character gains the ally trait until the end of the phase", can I activate it so that when Varys comes out of shadows (King's Landing: "when Varys comes out of Shadows choose and discard an ally character from play") he discards the character I gave the trait? If this is possible, in which steps can I activate the any phase effect in order to accomplish this?

I'm guessing no for all the answers, but as I explained before, I'd gladly hear from you the absolute answer. Thanks for your help!

No, no and no.

1&2: Both cost reductions apply to playing a card, which is not the same as placing the card during setup.

3: That action (giving the Ally trait) can be triggered after Varys has come out of shadows during that phase, so you wouldn't be able to discard the character because it's not an Ally when Varys comes into play. The Ally trait will dissappear at the end of the phase so it won't work for the next phase either.

Bringing a card out of shadows is the first thing you can do each phase and it's before any standard action (like the one you describe) can be taken. You could use that combo with Ser Arys Oakheart, though.

Thanks for the confirmations eloooooi!

Another question, if you could help me, it also has to do with agendas:

4 - Can I use Street of Steel to reduce the cost of Ranger of the Watch if I'm running The Rangers agenda? Ranger of the Watch doesn't have any icons per se, but is given a military one by the agenda. My doubt here is if the agenda aplies to cards in hand (or as they are being played) or not. I'm thinking the answer is "no", but, once again, I just wanted to make sure.

Thanks in advance for the help!

You can't reduce the cost of the ranger, 'cause when you pay for it he doesn't have any icons. He get's them once he hits the table, never before that.

Ok! Once again, thank you!