Self preservation is a nice healing card, but the best advantage I can see here, is that it's not restricted on heroes only, and you can use it on any characters, which make this card excellent bonus for important allies or in some cases also on targets which are for the purpose of the game taken as allies (as Glum in return to mirkwood, for example) and don't have restrictions on attachments. So this makes this card useful in specific scenarios or when you're running unique characters, important for the deck's mechanics. Artwork is also fine. Verdict: 4/5.

Self Preservation is a neat healing ability, if more expensive than most. But it's repeatable (unlike most other healing attachments), and not susceptible to direct damage (like most healing allies). One thing of note is that it will only heal the attached character, unlike the DotN.