All the time Gandalf was looking at the sensation and the intimacy between his sister and Olivia. It was so passionate that his phallus grew hard, he started stroking it softly until he released his seeds with haste.
Lord Aubrel was suspecting how the things were going in the tents and he found Gandalf in his own true nature, pleasing himself off the sex his sister was having. After he was done, he returned his manhood inside and rushed to his tent with haste while looking around.
The next day the journey continued to Prophis and the more they were close to the kingdom, the colder it got. Lack of experience in fighting the combat with the extreme weather rendered Gandalf's men unfit for a war in Prophis.
And hence that's when Gandalf decided to propose something to Lord Aubrel when they were drinking and having fun in their carriage.
"We should fight in a hot land, not in the snow. My soldiers are made for summer not winter" said Gandalf.