If you trigger the illusionist when bricks are falling, and the weapon stops the action with bricks that are offset from all the other stationary bricks, then a wierd bug can happen.
Move the falling brick (sometimes you can, sometimes you cant) to near the bottom of the screen. Place blocks on top of this one or not. When the illusion wears off, the block drops through and off the screen, taking any blocks on top of it too. You then can't lose your multiplier for about 15-20 seconds. About 15-20 seconds later, the fallen bricks mysteriously reappear! after that the game is back to normal.
Kind of a neat trick, but not too useful. If you can pull it off with the last illusionist weapon, you could use it to keep your multiplier for at least a while.