How does this card interact with account siphon? The runner would have priority, and account siphon activates on successfull run, just like Jon Massinori.

Jon Massinori activates on a successfull or unsuccessful run, and so does Account Siphon. The same thing would be valid for other alterantive to access cards, like Vamp.

I'd say when the run is declared successful first all runner on-success triggers resolve (Account Siphon run ability) and then all corp on-success triggers resolve (Black Level). It's the weirdest Siphon tech ever. The runner has two bad choices: Take 1 brain damage after his successful Siphon, but leaving Black Level where it is since Siphon replaces access OR use the jack-out-window offered by Black Level to trash it and give the corp creds directly after you siphoned them, negating the 'Siphon Lock'. —
Account Siphon replaces accesses, which you don't get if you choose to jack out. —
I think Protikon is right. The run becomes successful on step 5.4 of the timing chart, but Account Siphon doesn't do anything until the Access step 5.5, so Black Level Clearance always fires first. —
What Toper said is correct. I was mistaken about the point at which Siphon resolved. —

Haven't done a review yet, decided that this should be it.

Let me start with, this is a terrible card most of the time. It takes clicks to install things, sometimes credits to rez them. This card throws out all those clicks and creds, and gives you credits on hand. What this card actually is, is a stance change. You destroy everything that you've built for liquid capital, hoping that you've got enough cash to win with whatever your strategy is.

This card might be a counter to some runner techniques. IE - if they just installed Yog, this would let you recoup some of your credits for ICE that just became unusable. Or if the runner keeps bouncing off outermost ETR ice to build counters on Turning Wheel, you could sell the ICE.

The only other place I could see this card being useful, is in an asset\ICE spammy deck, with a kill package. The theory would be to build board state to a certain point, then pivot. You spend early game building board state. Sometime in midgame, play this card to remove unused\unusable assets. Then, play something like Midseasons to tag for a bajillion.

It may also be useful for some kind of CI7 combo, and Accelerated Diagnostics.

I used Liquidation to get mass credits for a guaranteed Punitive Kill. It does work, but it's a 'burn everything down for money' and win that turn. —
You can also play it into Midseason to effectively convert your cards into three tags each. It's a nice backup plan if they break into your remote in a way that makes it obvious you're not going to be able to lock them out well enough for it to count...just burn the whole thing down for tags! —
So, now that Friends in High Places is out, this card becomes slightly better. Trash 2 rezzed cards, gain 6 credits, play FiHP, reinstall 2 of those 3 trashed cards. Net total is 3 credits. Not great, but now the runner has to chase those cards are you do it again. Coupled with Bryan Stinson, and it's 0 credits 1 click to replay - slightly better. —