Taunt but no Smackdown with e.g. Decay

[[LOLl]Manu311]

I've played a few games the last days when I realised I get much kills and remembered to taunt them before I kill em but I'm the only one who damages them, I kill them (not a creep or sth) but with e.g. decay (devourer)
example Match:
Match 36061920
2 of my 3 taunts didn't worked because of that.

[[S2]Vahn]

Time stamps please.