Location:  Blighthaven at Grove of Hope; daily quest given by Drusera (Co-ords 3309, -3768). You will not need a group of 20+ for this tower defense event, it is easily solo-able.  The fastest way to complete this daily is to let the Strain infect The Tree of Life (aka Drusera's Tree) by allowing them to kill the Primal of Life. Once the tree is infected clear the Solarquake Anti-Primal which will cleanse the Tree of Life and start the next phase. There are three total phases each of which have a 'rest phase'. It should be noted that every 30-45 seconds an explosion will emanate from the base of the tree while infect, to avoid this explosion and knock back simply stand on the Red,  Blue, Yellow or Green crystals surrounding the outer perimeter of the tree. 

Remove: Double post.