****Slight Spoilers below*****
Having Elias in our party definatly made this scenario on the easier side with his teleport ability. We were able to completely by pass the level 3 tile and Elias was able to teleport into a room to pick up the firworks on the level 2 board while everyone else fought the enmies. He then was able to teleport out the other side then get onto the bridge lay the fireworks, attracting the immortal. Once the immortal arrived on the bridge Elias was able to finish off the pillars he had weakned before the immortal got on the bridge. (obviously this was done over a few rounds).
We also played this scenario yesterday and found out that the fireworks disappear at the end of the round when they are put on the map. So in our opinion you need at least two fireworks to get the Immortal the bridge as he only moves two spaces when he activates.
Can someone confirm this?