Spawn locations (click for map image) for your "heartoffearb.txt" map file (note: see this quest entry for all Heart of Fear named map points):
P -1737.0769, 1318.8379, -263.1062, 127, 0, 0, 1, Ixmilsh_the_Terrortangler
P -1749.7532, 1396.3625, -256.8422, 127, 0, 0, 1, Ixmilsh_the_Terrortangler
P -1833.1201, 1172.9788, -225.1566, 127, 0, 0, 1, Ixmilsh_the_Terrortangler
Known spawn locations, in-game /locs (PHs are "an enraged _____"):
-1320, 1740, -263
-1395, 1750, -256
-1175, 1835, -225
This is a named tentacle terror.
Casts Slap of Ages (most hated target nuke for 37,000 dmg) 5 seconds after engage, and then every 10 seconds.
Casts Fear Blast (random single target knockback + nuke for 42,000 dmg; will not his most hated target) 15 seconds after engage, and then every 20 seconds.