I think it'd be interesting to make the epic monsters a bit more like the enemies in Monster Hunter, with powerful, telegraphed attacks, varying combat strategies, and breakable parts.
Make Baron necessitate multiple people by having different objectives than "hit it". Maybe someone needs to channel and restrain it to keep it from using its most powerful attacks, or have people focus attacks on its head to blind it before its big combo comes out, or cut off smaller heads to limit the size of its AoE. No one should solo Baron.
Dragon buffs could also use a touchup. Some are phenomenal (Infernal), some can dominate games if you get one early, but don't really do anything for late game (Ocean), and some are just kinda meh. It'd be really cool if (following the Monster Hunter theme), dragons would drop a bunch of parts that each person could use to craft their own buff. If you want defenses, maybe take the scales. Damage could come from the claws or teeth, movement from the wings, etc., and each dragon would affect it differently. So the Infernal wings might give you movement speed after dealing damage, while the Mountain wings would give you movement speed after taking damage, stuff like that. Everybody could have a buff that is useful to them and tailored to their playstyle. I think dragons should be solo-able, but it should be more difficult and/or only something an objective-focused jungler can do.
