The home army are unchallenged, and are therefore able to march forward to the tower. They also have an active minor terrain, which has a 25% chance of giving them a magic action again, which they can use to either reinforce further, or attack the Treefolk reserves.
The reserve army only has the option to cast magic, which means Wind Walk or Resurrection, both of which are basically useless at the moment.
The big decision is whether to move to the Frontier, possibly encountering the Treefolk horde, or to go back to the Treefolk home terrain.
Frostwing 1st March
The reserve army roll for magic.
They produce 5 results and cast a Wind Walk on the home army.
Frostwing 2nd March
They roll the minor terrain die.
They get a melee action option.
The terrain die moves to face 4.
With no target for missile nor for melee, no further action can be taken.
The reserve army are deployed to the frontier as a new campaign army.