Can someone please explain to me how the attachement part of those characters work? Does the character it attaches to gain anything other than the text? Or does it again the strength and/or icons of the card the banner card? It seems if the character only gains the text these cards would be next to useless...

KainOfDreadwood said:

The attached character gains only what the text tells you it gains, of course. As you will have noticed, some Banners are not that great, really. The Baratheon ones are the best, because the keyword they give is useful. All related Banner-mechanics are gimmicky and overall just "meh", largely because there's hardly any support for this mechanic.