UPDATE: Consumables were removed from Diablo Immortal before the game launched Live.
Each class can loot one special consumable item from the Horadric Altar. Kill any mobs in the outdoor world for a chance to loot Monster Essence.
Bring 10 Monster Essence to the Horadric Altar. Not only will you add a permanet bonus to Life and Damage, after closing the book, you get a piñata of loot from the altar that includes materials and a consumable item.
HORN OF ARREAT
The Barbarian loots an account bound consumable that increases the damage of party members. Perfect for bosses with tons of health points and to annihilate elites and minions.
Horn of Arreat: Increase all damage done by you and your nearby allies by 10% for 20 minutes.
The Demon Hunter loots a consumable that increases party movement. Pretty good to speed run through Elder Rifts and future content.
Tracking Kit: Increase movement speed for you and your nearby allies by 10% for 20 minutes.
The Monk loots a consumable that is essential for every party member running an Elder Rift and Dungeons. Increased Magic Find! You will always want a Monk in your team.
Incense Candle: Increase the chance for magical equipment to be found by you and nearby allies by 5% for 20 minutes.
The remaining consumable belongs to the Wizard. I don’t have the tooltip at the moment, but I will add it when I find it from my past videos.
The Wizard consumable is the least benefitial to the party. It simply opens a portal to Westmarch that all party members can use. There is no gear repair mechanic at the moment in technical alpha. Not sure if it will be a thing when the game launches, but that’s how it has been for all Diablo games in the past.
In that case, when the mechanic is implemented in the game, and you have wiped a few times, teleporting to Westmarch for a quick repair or to empty your bags might be useful. It would be better if you could enter the portal and return to your team.