I think the spectral essence altar should be used for teleporting a player in a nearby 3 x 3 area around it. Then a gui will open asking which spectral altar they want to teleport to. spectral essence will be required to teleport. essence will double or triple in the amount required when teleporting to other dimensions. both altars must be supplied with essence to function.

New spectral idea:

think that the spectral altar should be used for overseeing things or like a security camera. You bind a transference gem to the alter and when you right click with the gem it uses a little bit of essence from the altar and allows you to look around from where the altar block is. you are able to open guis from the screen of the altar. Shift - right click to exit the altar screen and look back at player first person point of view. inventory will stay the same while in the altar's screen. in multi player a ender eye will be showed floating over the altar when the altar is being used.

Second idea:
put a nearby chest next to the altar and if the altar has enough essence in it, when you die your inventory will be saved into the chest. Items in toolbar will not be kept.

Some of the ideas are planned but not for the essence altar.

Like what?

Secret .P

Third idea:

Shield. Charge it using essence. uses essence every real life hour. Essence is used when the shield takes damage. Only players who are specified in the altars gui can walk through the sheild. Covers a ten by ten area around the altar.

Shield essence usage when damaged:
Zombie( mobs like a zombie): 1, Skeleton( Arrows ): 3, Creeper( TNT ): 10, Spider( Cave spider ): 2, Wither Skeleton: 5, Ghast( Ghast ball ): 10, Blaze: 5, Zombie Pigman:3, Slime( mobs like a slime like a glob from biomes o plenty): 4, Magma cube: 4,Enderman: 8, Wither( Wither skulls ): 15, Ender dragon: 20, Random mobs: 1 - 5

Mobs should take damage when they attack the shield. Projectiles damage shield and are reflected back at the mob. Altar can not be destroyed by a mob. Special block is placed by altar or an item is used to upgrade the altar to increase the shields area. Works with other altars like the fire essence altar to increase smelt speed or area the altar can power furnaces.

Fire essence altar idea:

Be able to power furnaces from other mods.

just an idea, change part of it if you only like half of one of my ideas

I'll move the ideas into a separate document to keep track, and then close the issue here so it stays clean.

is anything going to be added to the new altar?

Not now.

Transference Gem exists for that purpose, it's not acquirable in current version because of the redesign but it will be in one of the following updates.