Guardian Harell (click for map image) can spawn inside and outside of the Keeper's Tower (PH "a keeper of the hearth").
For your "arginhiz.txt" map file (note for all Argin-Hiz named map points, see this quest entry):
Guardian Harell casts "Guardian's Stance" (2-tick resists + AC buff); "Keeper's Blade" (single-target DD for 40,000 dmg + 2,500/tick DOT + 1-second stun); and "Toss Aside" (single-target knockback + spinstun + DD for 35,000 dmg).