The description for the achievement to unlock is as follows:
As Loki kill three or more enemy gods from behind.
What the description does not tell you is that the kills NEED TO BE ULTIMATES
. Regular kills from behind do not count toward this achievement (it has been tested and proven). In order to secure the kills we popped the daggers, invisibility, and then the ultimate.
Loki's forth ability (
or 4) is a teleport, stun, strike that inflicts some serious damage. As you level Loki up his ultimate does more and more damage depending on the build and can be a huge shock to fleeing enemies that do not have much health as it can easily kill a weakened opponent. For this specific achievement though you will find that the kill needs to be from the ultimate itself, not basic attacks you unleash after the ultimate hits making it a bit harder to net in regular games.