if you are going for fast xp then its imo best to go with 3 ppl (one max fw caster, one roguetype and one other, preferrably a healertype). do the tombs on normal (can do shadow knight on hard or leet and let the rogue do the traps. that does take a bit more time but gives substantial more xp) for quick completion. shadow king can be done on normal without pulling the boss to the cage as he is vulnerable for a good 2 seconds before becoming invulnerable. so a firewall + scorching ray fixes him.
this all can be done in 35 mins (or less) with a dedicated group. only one get the quest-chain update and you do the crypt on normal for the xp bonus. now the next can update chain and you do hard. with your last advancement you farm elite till youre tired or you figure the xp arent worth it anymore.
a usual shadow crypt run just for completion takes around 15 minutes. with extra chests around 20.
thats more like 250k xp in like 3 hours
i know you guys know that, but some might not.