Suggestion: ARAM Epic Monster

ARAM game mode except there's a boss pit in the north-west corner with two entrances like Vilemaw's.

Boss could have Freljord flavor (possibly Anivia, as powerful as Xerath in Ascension game mode).

This would give a chance for champions who are better at objectives to shine in a randomized champion selection and provide more strategic options in ARAM like forcing fights at objectives and flanking from jungle paths. Also more walls, which helps champs who interact with walls like Bard. Teleport would become relevant. Basically, a lot of elements of league currently lacking in ARAM would become supported without disrupting the essential "All Random All Mid" feeling.