The Power of the Finger
Adrian is currently sensing the changing nature of the Quantum Corridor. He could sense that the Arch Lich is trying to force his way through the entrapment but it could not muster enough force to break through completely. Adrian sighed with relief when he could feel the effectiveness of the spell.
It was just really bad timing that he got hit by backlash when they successfully cast the Quantum Corridor. The Arch Lich spell hit the magic circle of the Quantum Corridor when it was just spreading to the area. Area of effect spells are most vulnerable during the start of the spell as it still has a connection to the casters hence Adrian being damaged.
Since the phenomena of the spell is already set, the spell matrix is already complete. This is the reason why the spell is not influenced by a foreign magic spell but is instead directed to the caster. It is like a post spell version of mana overload but it is called "Spell Backlash" by the players in Pandemonium.