I'm trying to reconcile the rules around the Banner of the King.
The Banner is "unfurled" (comes into play) after Gandalf casts the Spell "Reveal Aragron to Sauron." The duration of the Spell is three Game-Turns, which I interpret to mean the current turn plus the following two turns.
The proximate effect of the Spell is to place the Banner in the same hex as Aragorn. The Banner functions much like a Leader in terms of movement, combat, ZOC, etc.
The other effects of the banner are described in rule 18.2:
[18.2] EFFECTS OF THE BANNER
[18.21] No Sauron Leader may attempt to Rally any Sauron combat unit that is within six hexes of the Banner.
[18.22] For the three consecutive Game-Turns in which the Banner is unfurled, any two Westernesse units (per turn) within six hexes of the Banner are automatically rallied.
[18.23] The Lord of the Nazgul man not attempt any Spells while the Banner is unfurled and in play.
One reading of this is that the Banner exists for three turns, and during those turns, the three effects above are in play. In this reading, the extra language in 18.22 above is superfluous, and could be removed.
Another reading of this is that the Banner exists indefinitely (i.e., until it is eliminated), and that the effects of 18.21 and 18.23 are indefinite, but 18.22 lasts only the three turns.
My sense is that the first reading fits better with the idea of the 3-turn Spell duration, and that all of the effects of the Banner last only three turns. And rule 18.14 (about elimination of the Banner) is only relevant during those three turns. In game terms the Banner is removed; but in real terms, the Banner would still be there; it just would not have the shock effects any longer.