It's a very situational item.

/if/ you are a melee hero without much chasing power but wants early game kills in situations where supports might not be available to help.
/if/ you are against heroes who are going to farm and you absolutely need to prevent them from farming, /unless/ you are going to be attacking more than once every 2 seconds, in which case just put the money towards wraith.

If you just want to spend gold and wards are on cd, buy tps/sentries/dust/smoke/tangos, these will almost always be useful in every game.