In DotA, when the Spectre uses Haunt, there is a global sound effect that indicates to every player "Holy crap, Spectre just ulted, he might just come rape me now."
In HoN, the sound for Sand Wraith's Mirage is not global, nor is it very distinct. You can hear the sound if the Sand Wraith uses his ult near you, but you can't otherwise. This makes it especially confusing when a SW grabs an invis rune, pops out and attacks you, and you don't immediately know if it's an image from Mirage or the real thing (because you didn't hear any sounds indicating that he ulted).
Heroes with global ults should have global sound effects. It's helpful information for both your enemies (to know that they might get ganked by SW) and your allies (to know that a SW is initiating or ganking).
I can agree with this, global ulti's should have global sounds.