Zaviak's Vision Quest

Zaviak's Vision is an interesting quest in which you use a certain item to find and interact creatures you can't normally see in the Prime Material Plane, adding a lot of exploring elements while adventuring in the Siege of Dragonspear world.

Talk to Zaviak in Elfsong Tavern in Chapter 7 (SoD) and you'll receive a pair of Spectacles of Spectacle, by wearing it you'll be able to see creatures in other overlaping planes, to interact with them however, you'll have to consume charges to "pull" them to the Prime Material Plane where you exist. The item has 3 non-rechargeable charges but there're a total of 9 spots where you can use them, listed as follows, choose how to spend your charges wisely, saving beforehand is recommanded.
 * 1) Al-Alai - Chapter 7,  Elfsong Tavern; H ostile fire elemental worth 6000 XP
 * 2) Gauth - Chapter 8, Coast Way Crossing NW ; C an be convinced to join the Dragonspear Castle assult with you, otherwise you may kill it for 6000 XP and Ring of Fire Resistance
 * 3) Greater Shadow - Chapter 9, Bugbear Caverns in Forest of Wyrms ; C an be convinced to fight the Bugbears for you; otherwise nets 3000 XP
 * 4) Nazramu - Chapter 10, Coalition Camp; Sells Wizzard Hat, Bracers of the Shuttered Lid, Dervish Crescent +2, Cloverleaf, Ring of Free Action, Ring of Purity, Amulet of Protection, Necklace of Form Stability, Dusty Rose Ioun Stone, Bracers of AC 5 and Gauntlets of Weapon Expertise, h e sells high buys high, thus can be a good merchant to empty your spoils;  if killed nets 10000 XP and the Jester's Bracers.
 * 5) Greater Earth Elemental or  Raeanndra - Chapter 10, Dead Man's Pass NE; Earth Elemental attacks after dialogue and nets 4 Emeralds and 11000 XP,  Raeanndra  the Tiefling gives you the Ring of the Tiny Fiend as a reward, and if killed, nets 2500 XP, gems, potions a Studded Leather Armor +2, Wazikashi +1 and Ninjato+1
 * 6) Vidyadhar - Chapter 10, Underground River Caverns NE; this Rakshasa gives you Modron Heart as a reward if you solve his riddle ("Bees") before teleporting away, and if killed, nets 10000 XP, Modron Heart, a Scroll of Protection from Magic and a Scimitar +3
 * 7) Zhadroth - Chapter 10, Kanalgym; this Lich gives you the Ring of Regeneration as a reward, and if killed, nets 22000 XP, the ring and the Robe of Arcane Aptitude. After freeing the Lich, whether you killed it or not, an Endless Watcher will show up at the area entrance, nets 9000 XP and Astral Crossbow +2 after being killed
 * 8) Idyletia - Chapter 12, Avernus entrance; this Deva teleports away after finishing of a green and a red Abishai, and if killed, nets 15000 XP
 * 9) Xhost - Chapter 12, Avernus elevator zone; this Demon attacks on sight and when his health is brought to half, he offers you Gift of the Demon +5 in exchange for his life, nets 12000 XP if killed

Reference

 * justfeelinathome's post in this thread