Reference

Settings: many, including a variety of Ardas (the setting of the Silmarillion). 

Main templates: Bells and Maitimos, or Fëanorians more generally

Prerequisites:

All prerequisites are optional but contain helpful context. They are all readable standalone.

Luminosity & Radiance is quite long and worth reading first. Worm is also infamously long [NB: the creator of this reference hasn't read it]. The other prerequisites listed are shortnot very long (longest is Eclipse) and can probably be read interspersed with Silmaril itself.

Subcontinuity	Prerequisite(s)	Map of known worlds (made by phi)
Elentári	seidr and spear	-
Telperion	in which the prime directive	-
Defy Your Limitations	Daevinity	-
North	Bindings	Map 0 (post North)
East	Luminosity & Radiance	Map 1 (post East)
Shine	Geode	Map 2 (post Shine)
West	groundhog day	Map 3 (post West)
South	none-	Map 4 (post South)
Kandrona	none-	Map 5 (post Kandrona)
Southwest	Eclipse	Map 6 (post Southwest)
untitled 1	none-	Map 7 (post untitled 1)
Unbreakable Vow	the first page of either Bluebell Flames or Witchlight	-
untitled 2	none-	Map 8 (post untitled 2)
Disappear	-	Map 9 (post Disappear)
shard	Worm	-
Starstone		-

Content warnings:

Authors did not use content warnings.

Silmaril contains:

characterized being traumatized from the aftermath of being tortured by evil gods (the evil god torture is offscreen, mostly) also a bit of regular, non-evil-god rape and domestic abuse (mainly in subcontinuity "shard")

Spoilers:

Subcontinuity "West" contains major spoilers for Puella Magi Madoka Magica.