So this a common bug which I do not know how to reproduce, but seems to happen at least 1/8 games for me or one of my friends I am playing with.

It seems that sometimes you can just up and walk through walls... Yes sir...

I was using Malphite (and doing good I might add) when after I solo'd Dragon, a enemy Pantheon was waiting for me outside of the dragon spawn. He knew he could not take me so he waited their for back up. Not knowing what to do, and not wanting to waste my flash or Malphite ult, I walked back and forth until my team arrived.

Fortunately I did not even need them, nor did I need flash or my ult. I just walked through the wall...

Although extremely useful, it is a huge problem. Please fix this

I just saw Trynd do this with his slash. I was going to get one more hit on him, and he spun right through the wall. I'm pretty sure the spell isn't supposed to slice and dice through walls. But maybe thats just me.
Any other heros that can walk through walls? Probably shen can do it. That seems like it would be something he could do...

trynd can spin through the wall,
if you didn't use any abilities and your malphite just walk through the wall then its bug

Yes, there are places in the map where this can happen.

Attached image shows the places that I know of that this can happen.

It's a serious error, can we get a Red confirm?

I have had this a few times as Karthus, once early laning in mid, i just walked back and then he up and walked through the wall into the Wraiths... I have walked through the river ledge too, i was up along the side putting lay waste in to check it and then he just walked down the edge into the bushes...
So you can update that map :P

spamming the same bug for about 100 times by 100 different people and about 20 replies from riot wont make the bug go away any faster.

I had the same thing happen to me, I was playin swain and we had just tower dove inside of their base to get a kill, so I walked up to a wall to flash out and instead walked right out of their base through the wall. Only time it's happened to me though.

I think they were purple and it was between bottom and mid lane if that helps anyone to try and re-create it.

as shaco i very often stand on one side of a wall and cast Deceive on the other. I teleport thru it.
Tristana can rocket jump over 95% of walls too.

I've walked through the wall as Kennen before (so no chance of me using an ability that would do this), I think it was the wall behind red buff. It's like I got stuck on the wall and it pushed me to the other side. And people stop posting about abilities like rocket jump, deceive, dash, and slash, this is an actual bug.

We are currently testing a fix. Patience! =D