Could we have one? This is becoming an universe on its on, the rito-verse. Than we could have "dedpull kills the rito-verse".
Baron looks like Nagakabouros, it isn't the same but the serpentine body, the head with its eyes and teeth and the whole thing looks like they're related by DNA. The god (Naga..) may not be the sea monster itself we see but regardless, the sea monster does look like Baron.
Well some champs do have some 4th-wall breaking lines,but I think a full champ based on this would be a bit too weird considering that the general direction of the game is a more serious tone(though I wouldn't say its impossible).
As for Nagakaborous: Illaoi says that nagakaborous has many forms,she may appear as a hydra,sea serpent,kraken,etc. What you are referring to is a krakenwyrm I think,its pretty much the form that the people in bilgewater associate with nagakaborous
brakes the 4th wall, he knows he's just a character in a videogame..
"You only need to click once. Fool" 
More innovation, less copying.
as far as breaking the 4th wall goes, i only know is capable of doing this
alternatively, 
, 
an 
both have one quote that mentions the summoner
Considering one main motivation behind retconing the lore was to stop the breaking of the 4th wall, I don't think that'll happen.
too
Ye I realised a bit after posting that champions do that a lot :| hm I guess to itensify it one could refer to the game, code, Rioters themselfs as oppose to talking to the summoner who is non-existent now.
duhh sorry D:
