Asheron's Call 1:
I had winamp on random and I had just gone into an olthoi lair. The lobby scene music from The Matrix came on right as a wave of olthoi came crashing in like a tidal wave. I put my back in a corner and began dealing crushing blows with my hammer. One after another they were dropping, the music seemed to be pumping to the beat of my swings. As the last one fell, the music ended. I've never had such a perfectly choreographed fight before or since.
World of Warcraft:
Back before battlegrounds and whatnot when world PVP was still fairly fresh me and my buddy snuck in to Hammerfall in Arathi Highlands. I hid in a shed, and my buddy, a gnome went under the buildings he was blasting the ankles of the horde with his fireballs. The only way they could attack him was to go inside the building, but as soon as they did, he'd come out from under it. Slowly he whittled down the masses, my pally occasionally popping him with a heal from his hiding spot. Then a shammy came and dropped totems that could target my mage friend under the buildings. It looked like it was all finished for my gnome friend until I popped out and begain wailing on the shaman and popped a full heal on the mage. We left victorious and well-feared.
