Ok, so my sister had this idea where there is a buff that randomly spawns in a bush on your side of the jungle.
Randomness is generally frowned upon in LoL, and has been removed in several instances since the game's launch. Critical Strike Chance is among the few remaining RNG-based mechanics.
For you're suggestion in particular though: the go-to jungler item for a long time was called Madred's Razors. When LoL launched, it gave a random (~25%) chance to deal a substantial amount of magic damage to minions and monsters.
Some times a jungler would get lucky, clear camps very fast and be able to surprise-gank a lane earlier than expected, other times a jungler would have a very slow start that's hard to recover from.
That item was later changed to apply a set amount of magic-damage each hit, because the random nature of the procs where seriously messing up initial clear-times for junglers.
Also in regards to jungles - the monster camps in Twisted Treelines used to spawn ~3 different randomized mob camps in a few zones. With the current reworked Treelines - all mob camps spawn the same monsters 100% of the time for similar reasons as the Madred's Razor change.
While Madred's Razor's are long-gone: there is no longer anything random about the jungle: regardless of what map mode you look at.
I mean - you could have an awful start where, despite doing everything right, your buff spawns in the worst possible location for finding it and your opponent just gets theirs handed to them at the optimal time, then finds yours when going to gank one of your lanes: giving them a massive advantage in early-game dominance solely because RNG favored them.