Cosmic Slayer

Don't see this mentioned anywhere explicitly so will write so it is known:

There are currently THREE eligible creatures for this achieve, two in Eversong and one in ZA.

Eversong Void Strikes:
- Void Ritual: Springclaw (Giant Cat boss)
- Void Ritual: Croaker (Giant Frog boss)

Zul'Aman Void Strikes:
- Void Ritual: Grizzly! (Giant Bear boss)

Therefore if you are farming for achieve you have better odds doing it on the week the strikes are in Eversong, Happy hunting!

We did it!! Thank you for your help reporting this!!

"Fixed a bug that could prevent some players who were properly in combat with the Void-Corrupted creature from receiving credit toward the Cosmic Slayer achievement."

Please Guys Report this as Bug so we get a fix soon. Thank You

Coppy this text in Bug Report:

"The ACM "Cosmic Slayer" is not working as intended you only got count for it if you got the last hit on the Boss which killed it (Killing Blow). Please fix this soon as you cant finish the acm by luck when 40+ people are hitting the Boss. Thank you!"

Guys we can do it as we could as The Love armor Proto drake. Please all Help it takes less then 2 min....

Thank you

When the Void Strikes are in Eversong Woods for the week, only the bosses found at Void Ritual: Springclaw and Void Ritual: Croaker count towards this achievement.
If a different strike is up, you will have to wait for that event to finish for the location to rotate.

This is still a pretty terrible achievement after the bug fix given that you have to wait for 2 out of the ~10 Void Strikes.
Also anecdotally, Void Strikes seem to rotate anticlockwise in a circle.