It seems to me his main goal is to take down the DIKs. The pics in the first instance at the end of Ep 2 were meant to make them think it was the DIKs who sent them because, aside from Chad's, it shows various DIKs having sex with Arieth. Chad's pics are cleary those of him and Troy based on his reaction but we still have no idea if there were ever anything written in the envelopes because all we know is there was pictures. So by making it seem like the DIKs did this, Magnar's trying to provoke the Jocks into all-out war with them. Chad'e pictures were probably meant to oust him by exposing him because Dawe was probably much more likely to wage war against the DIKs than Chad since Dawe is even more of a hot-head.
Then we have the Cathy pic which was probably also done by Magnar, or at least by Ron, and was something else meant to get the DIKs in serious trouble with the college and the 2nd batch of pics to the Jocks plus what he sent to Tybalt are to try and reignite exposing things the DIKs have been doing in order to get them disbanded.
So thus far, all Magnar's actions seem to be against the DIKs and he pretty much confirms they are his target and the rest are collateral, "The DIKs won't see the dawn of spring. And like a house of cards, they all shall fall."
Right, because we had some paradigm shifts, like Quinn's status in the story changing by the end, Rio being totally done with Quinn, the DIKs being in disarray and Nick quitting them, Magnar being revealed as this scheming little weasel. So the title lived up to it with these and other things happening.
They don't have to, really. Magnar feels like the appetizer bad guy before the main meal of Vinny, Buddy, and Burke. His scheme is so petty and pathetic that if it just ends up with something like Sally ratting him out to the MC because she doesn't side with him then that's fine if it does because that's all it really deserves.
I honestly don't see Magnar being a serious threat that deserves some high drama plotline with deeper threads. The man's just hacking into stuff and digging up dirt on the DIKs to take them down for some as-yet unknown beef.
Don't take it so literally