• In which format do the spikes occur: 3v3, 5v5, ARAM, unranked, ranked, etc?
I generally only play 3v3, so I can't really say if the spikes happen in the other games modes.
• Does it happen at a particular time/location: during team fights, when you’re at spawn, randomly, etc?
Happens at random.
• How often are the spikes?
Again, at random intervals. Sometimes I'll go an entire game without a spike, sometimes I'll get a spike ten minutes in, sometimes, I won't even be able to get into the game because of it.
• How long do they last?
Anywhere between two and ten minutes.
• What symptom(s) do you see during spikes: champion “ice-skating” or jumping around, game hitches, etc?
My champion will react to any command I give, however, I can't see any opposing champion movement. I can only see my own teams movements. I can watch health bars drop, with no idea as to where the enemy is. Minions will freeze in place momentarily, and then begin to slide from where they stopped to where I assume they have moved to, appearing to still be targetting whatever it was they were last targetting, wherever that has moved to.
• What’s your ISP?
AT&T in Monterey, CA
• Do the spikes only happen in LoL?