The Soldiers weren't affected by Magnus' roar nor his fire, the fire that he spewed at them actually backfired and lit the hovercraft on fire and hit some of the Marines. The Marines were losing the battle and Magnus made it worse for them, the last of them that were alive and wounded started to retreat from the soldiers but were gunned down. While those troops were fighting a mass of wires fired from the portal and wrapped around Magnus, they started to pull the dragon towards the portal. 

When Ivory witnessed the portal she was already gone from the bridge and was outside, another large group of soldiers dropped in and were instantly ambushed Ivory, she dropped down in the middle of them and used the same room clearing move it used when she arrived on the hover craft, the explosives blew the soldiers apart but some of them were still alive and tried to shoot the machine, but Ivory just dodged their attacks and counted by firing back at them with her shotgun within her arm. The other Soldiers already made their way inside and started to kill non-combative crew members.