The "50-final-blow kills" achievement is largely doable if you sit in the back of a zerg and spam your class execute, such as Jesus Beam or Mage's Fury. Executes proc at low health and burst quickly enough to land you the final blow. If you don't have a class execute, then you'll struggle somewhat because everyone else will get the killing blow 99% of the time.
Also equip Soul Assault and stack Max Magicka, crit chance, crit damage, and spell damage. For sustain, use a Lightning Staff HA with an Oblivion Damage Enchantment equipped. For extra burst, you can use Valkyn Skoria, as it will proc off of Jesus Beam (if Temp), Soul Assault, and your HA channeled ticks - all of which are DoTs. Meteor is not advised as it takes a few seconds to land, allowing time for the target to get killed by something else before the Meteor lands.
If you can't find a zerg, make a zerg. If a zerg cannot be made, join a guild and host a guild event where 20+ of you go into IC all on your Wardens and trample every Procblade in an unholy stampede of Birds, Bees, and Bears!
Edited by Vercingetorix on July 19, 2017 1:43PM “Let your plans be dark and impenetrable as night, and when you move, fall like a thunderbolt.”