Complex sentence: Templar and his squad are called back to the base for reassignment however the ISA HQ is overrun by the overwhelming assault force of the swarming Helghast and a forced evacuation is conducted.
Split into simpler sentences: Templar and his squad are called back to the base for reassignment. However, the ISA HQ is overrun by the overwhelming assault force of the swarming Helghast and a forced evacuation is conducted.