I think that I spent my "Demigod MP noobness" in DotA, which was a pretty damn harsh introduction into this style of game.
My friend and I usually do a lot of comp stomps inbetween MP pub games and he tends to keep upping the difficulty stacking (ugh, us 2 vs 5 nightmare AI Regulus) and usually I use those comp stomp sessions to try out different Demigods, skill builds and item builds so that I know what I want and what to aim for once I do play a MP pub game.
If there was one drastic surprise from playing my first MP Demigod match, I think it's how you rarely ever get to level 20 and multiple Artifact items are very rare.
"What, No Ashkandor, Bulwarks, Unmaker and All-Father Ring in my inventory at the end of the match
?"