Please, help me understan better marsalling phase.

Can I kneel Godswood and street of steel cards to reduce the caost of Jon Snow to 0 gold? And so play this card whith no cold spending?

godswood would not reduce the cost of Jon Snow as he is not a Stark (what the wolf head on Godswood represents) character.

If you were trying to pay for Trident Reinforcements with a godswood and a street fo steel you could reduce the cost down to 0 gold and play the reinforcements for free (just like they were a card with 0 cost).

Ok. I understand. Another question please: Godswood can only reduce cost of Eddard, Bran, Catalyn, Arya, Robb, Sansa? Because they Have Stark -in there card name?

No the Dire Wolf's head reprsents any card with the House Stark affiliation. So any character with the Dire Wolf shield in the upper right corner can be reduced by two with Godswood.

Ok. Thanks. now I unerstand.