Ah, I assumed it'd be over. Can you drop it though? Mord is shooting fish in a barrel.Primus will keep the barrier up until they break through or he uses his concentration on something else. It lasts 10 minutes. Unless we need to go that way, why make it easier for them to flank us?
Mord should easily discern the spell as being an illusion based purely on his inability to see through it. And walking in might be construed as physical interaction?