Personally I love the feeling of when a low health enemy tries to flash away from an inescapable ability and then dies from it. Example: Naut's ult or Maokai's twisted advance, nope you didn't escape but you did waste flash.
What are yours?
I've had two Pentas in the span of 8 days. One of the greatest video game achievements I have ever accomplished.
Sniping someone with Requiem is awesome. Turning around a fight with TP is also a wonderful feeling for much the same reason.
To crush my enemies, to see them driven before me, and to hear the lamentations of their summoners.
Also Multi kills with Requiem or out fighting a strong Enemy as Vel'Koz
I love when I get into a teamfight as TF, and one of the enemy team members aren't there so we finish the teamfight and if we won I'll ult in on the last guy so we can push like madmen. (assassin TF, amazing at killing ANYONE from a bush)
I love kiting, even if I die. The experience of just trying to get away with all your might is awesome.
To me the best part about 
ry in LoL is when your earn it by not just outplayin ur enemy in skills and reactions but use ur knowledge and cunning to out think them and counter there own moves and gameplans. Nothin is more satisfiying then then dropin a pink ward ward on a 
who thinks she's safe or a buyin mid game thornmail as an ADC an watch a 
fail at tryin to soloin u over an over again. But my all time favorite move was to Tower bait with 
. I would take 
& 
and let the enemy shove the lane and bully me till i was low. After a min or two they would dive me usually with junglers help. I would pop eat the damage, Ulti then heal, and with more then 1/2 my health back and at full rage under my tower with Ulti engaged, well there were to many double kills to remember, good times :'). Nothins better then makin the other guy feel stupid.
When you're counterjungling and get caught out and chased, but you manage to take one of the chasers down just before you die.
Penta-kill with my man the boniest of them all 
its just to satisfying to see oh im no where near you BOOM GOES THE DYNAMITE SOMEONE CALL AN AMBULANCE SHOTS FIRD
I had two firsts that were incredibly memorable for me: first pentakill (
) especially since I chased the enemy team through their top side jungle from mid to top lane, took three turrets and an inhib before closing out the nexus turrets for the game. Second was my first baron steal (
), the enemy team was trying to sneak a desperation baron and we had no vision anywhere topside, we had three pushing bot lane while Elise and I went to check baron, tossed a random barrel just to harass them if they were doing baron (neither Elise nor I wanted to get too close since they had a blitz who could just hook us over the wall), didn't know if they were actually doing it and got the steal anyways.
For actually rewarding plays, really any time I play a champion the way they're meant to be played, any time I outplay my opponent mechanically or strategically, any time I play the map well and can apply pressure to more than just my lane opponent. Makes me feel like I actually know what I'm doing, and that I'm improving as a player :P.
Whenever I make a particular Skeletons R useless.
