I got 2 moments when i had the best steal
1/ When i stole baron with Braum's ult: i just ward baron and i saw them taking baron so i just ult and i actually took it :) 2/ stole Drake with renekton: saw them taking drake so i jump in like a mad man and stole it with my q/ult/smite(not sure which) and got a kill b4 i died.
comment you est momment below XDXDXDXD
I was azir so I put a soldier in the elder dragon ring thing, and they underestimated my damage so they just kept attacking it and I ended up stealing it xD
Playing 
Use blue trinket/Tracker's Knife to have vision.
Ult in before vision wears off and smite while I'm in flight from near maximum range.
I've pissed off a number of enemy teams by doing this with Baron/Dragon.
I stole baron with 
force pulse. I died because i forgot to use 
active.
I was playing Janna and managed to steal a baron from five men all alone by using my Q, their jungler probably wanted to kill himself that moment
