Toz focused on expanding the sheet of void metal while covering it in a thick layer of void magic that shielded the passengers from the Void. Since he was creating such a large magic construct and using so much mana at once, Toz burned through the mana potions like wildfire on a grassy plain during a drought.
But there were enough mana potions for an entire army, and it looked like it would be enough for Toz to make a large enough sheet to fit all the troops. And when he finished, he wouldn't have to expend as much mana as before. He would only have to maintain the sheet and the void magic to keep everyone safe.
However, there was one thing they had to do before that. They had to start moving. Since Toz was so busy creating the sheet and making it large enough to fit an entire army, he didn't have enough mental leeway or mana to move it around as well.
