Crystalline Passage is low level mobs
Once in main floor of Crystal Temple there are 4 portals
Each portal leads to another floor, there are 4 copies of the same map (one through each portal)
On the north/west/south/east maps, the portal will return you to main CT floor
At time of writing, Guardians are on a 1 hour respawn, two per map (total 8)
Also at time of writing, the main boss and associated spawns are on an 8 hour cycle
When that spawns, the portals will be guarded by SvaltusKnights, which drop frost guards
There will also be 8 IcePillars (2 on each map) which are protected by FrostGiants. The Pillars drop PowerOrbs
When you have all 8 PowerOrbs, return to the centre of the main map, where you'll be able to aweken SvaltusTrollKing
Be careful, he is also protected by traps, and by SvaltusElites, and he can revive the dead!