Kind of off topic but, if you really think two heart strikes and a death strike dont out damage a plague strike, icy touch, and hs then either your gear is retardedly bad or you have NO idea what your talking about.
Just use your head. In either case you have one HS...so the difference is a HS, DS and PS, IT...again use your head. Oh you get a glyph of what dark death in, whatever not like death coil hits for anything anyway.