This card is scary, and for good reason. Notice whose branding is at the bottom left corner? Yeah, this belongs in Jinteki for a major reason: Jinteki specializes in dealing massive amounts of net damage to underprepared/unsuspecting Runners. If you're running a Jinteki deck of any sort that focuses on net damage punishment, this is probably a good card to pack. Essentially, you're saving a net damage for later use. That huge line of blue applies here: if the Runner is unfortunate to hit your guard dog or its baby without a killer or credits, you can stack each net damage subroutine onto Prāna Condenser and, if I'm reading this right, gain 3 for each net damage. In other words, hitting a Komainu with a full grip will net the Corp 15.
As for the Runner side, this should be a high-priority target for you. Yes, it's expensive to trash, but 4 instead of a lethal amount of net damage is something you shouldn't spend too much time weighing in on. Unless you have a reliable way to prevent net damage (sorry, the only ones that come to mind for me are Feedback Filter and Guru Davinder), this thing needs to go ASAP. Freedom shouldn't have too much trouble, as well as Imp with a few spare virus counters, but odds are if this thing's hitting the table, you're going to have a very bad time until you get rid of it.
Finally, the flavor text really hits home. If your mind is its own echo chamber, the psychic agony can become unbearable...
Prāna Condenser may only prevent 1 net damage per source.— Koschei
It does only let you prevent 1 net damage per source, however cards like Komainu and Pup have multiple sources of net damage. Each sub-routine becomes it's own individual source of net damage, so you could prevent all 5 of them to gain five counters and 15 credits, or you could prevent any number of them.— Jesus_Phish