First ever ingame 13x on Triple Down (skip to 15.00). Everything is put on the four ogres in wave 12. The barrels in that secret room are put to good use in order to get the highest possible combo on Triple Down, a 13x, worth 204,800 points. The barrels do add a combo point, but you don't have to bring along the barrels for the combo point to be applied. In theory, you could score nearly 900,000 points, of which more than 90% comes from 4 ogres. That is worth discarding every combo on other enemies and drop the barricades.
Of the last four ogres, one glitched to death (no combo), one 9x, one 13x and one 7x. That's nearly 205K of one ogre, which leaves about 80K of points for every other enemy on the level, including those 2 other ogres of round 12.