Column of Crystal

The Illusionist conjures forth an illusory column of crystal. All that see it believe it to be utterly impenetrable.
Remains in Play. Place a large (5") blast template so
that its central hole is within 9" of the caster. Whilst
in play, the template does not move and is treated
as impassable terrain over which no line of sight can
be drawn.
"Yes, it should fit in there just fine..."