8 rits, no doubt you can and should spam every rit spirit there is.
add in 1 MM rit with bone fiends, and what you get is the biggest spirit forest you've ever seen. Imagine 20-30 spirits all with high spawning power and armor of unfeeling.
I tried this build actually in DOA HM, it's really slow but it get's the job done (it fails in gloom cave and foundry though).
So yeah, it has no speed, but as long as you are not in a hurry and you have room to pull, it's unstoppable.
I second Rt, they can do quite a lot even without using their secondary profession. Hex removal requires secondary though. You could even have a spirit tank:
Restoration 12+3+1, Spawning 12+1
Ritual Lord + Rejuvenation would then give a lvl 26 spirit with 790hp and 158AL. With that amount of armor, they would take average 33dmg/sec from a Bladed Aatxe, compared to average 183dmg/sec against a 60AL caster. Place spirit, pull foes on spirit so all melee's ball up on spirit, then hit them with for example 5 simultaneous Spirit Rifts for Cracked armor ~600 AoE. Place ranger traps under spirit for a bit extra fun.
I think Wastrel's Worry on an entire team of Mesmers combined with all their interrupts would waste most enemies faster than Ritualists could manage (with spirits limited to one of a kind as they are).
As Far As optionals go for the player, extra rupts or blackout would be handy against any really tough foes/areas apart from tht summon ice imp for extra snare, LoD for hiddens in dungeons, Wisdom for spell casting, Evas FH or YMLaD for extra damage (doubt ull need it due to wastrels spam on everything with no energy run out).
Hands down the most important thing about Soul Reaping it requires no skill slots AND barely any attribute points to be good = godly profession for multiclassing.
On a side note, besides the super popular NRt for heals or NMo for MM+Prot, I also recommend NMe, specifically for Illusion (convert Razah). Illusion doesn't benefit much going past 12 attribute and the casts are 2secs or less anyway, like many necro spells). The line is better on a necro because all the important spells cost 10e and you save a lot of space not fitting PowerDrain/DrainEnchantment/WNWN on the bar like a mesmer would.
Also, I'm currently experimenting with a NRt SoGM hero. SoGM on an Rt is okay, but the offensive spirits have crazy high costs without Soul Twisting (three 15e, one 25e). Boon of Creation somewhat mitigates this, but again I'm looking for max energy recovery and bar compression
Yes, but read the first post of this thread and the title. And I don't invest much in Spawning Power unless I have one SoS and the other SoGM, but even then I might not.