Defensive Ritualist??

Actually about SY I merely meant bringing SY (As in, putting it in your W or P or even A build, as opposed to bringing a dedicated imbagon).. but whatever mine was more of a joke than a real suggestion.

As for AP, I played an AP + spirits and then AP in Discord build pretty intensively when getting Guardian (when SoS wasn't OP) and I can assure you that even in HM you'll likely pull off AP most of the times, with practice. Thus, imho it seems a nice choice for a build like this, and gives you far superior energy managment to Reclaim Essence. Now, SoS+Siphon is still better in terms of energy and added damage but it doesn't recharge Shelter, which was kinda the main point, meh.

This reminds me of an old defensive rit build that i used to run ages ago, its a high energy build that managed pretty decent e-managed...least i thought it was decent back then.
If anybody wants to give it a try it was something like this:

Communing 12 + 1
Spawning power 12 + 1 + 1

Ritual Lord [E]
Boon of creation
Shelter
Union
Displacement
Empowerment
Mighty was Vorizun
Flesh of my flesh

Think its on pvx somewhere.
I'd drop rez for Armour of Unfeeling now its been buffed. Oh and i'd advise not bringing an MM if your going to be running this else you'l find that your spirits often die the second you put them up.

Also, +energy is not energy management. Boon of Creation helps, but I'd think you would still need some other sort of energy management, which is why most go with Spirit Siphon.

Frankly, I'd use this build:

Communing- 13 (12+1)
Channeling- 9 (8+1)
Spawning Power- 14 (10+4)

-Ritual Lord
-Boon of Creation
-Signet of Creation / Summon Spirits (or optional)
-Shelter
-Displacement
-Union
-Armor of Unfeeling
-Spirit Siphon

Or if you can multitask with it well, go /A and invest in Deadly Arts instead of Channeling and take Assassin's Promise. This would be a better option seeing as Armor of Unfeeling places a buff on your spirits, therefor is tricky when you are recasting spirits a lot.

Ultimately, it's all in preference. Frankly, I like Ritual Lord for it's unconditional recharge lowering. even if your spirits die quickly, they'll be recharged in like... 11 seconds.

For Heroes, I would use Assassin's Promise and stay away from Spirit Siphon. Players can use it well (using if between casting spirits, or moving around to target different spirits), but heroes not so much.

By personal preference, I like to leave Shelter out of it and slap a few healing skills on the bar instead.

Rit Lord/Reclaim/SoS/Offering of Spirit/Wanderlust/Soul Twisting/Spirit Challeling/AP or whatever you need really, the real elite skills are siphon and summon.
Shelter
Union
Displacement
Summon Spirits
Armor of Unfeeling
Spirit's Gift
Siphon Spirit

16 communing
11 channeling or spawning
9 channeling or spawning(i forget which worked better, one's better for energy, one for if you need the spirits with the most HP if you can get a battery or better depending on your elite)

^that works, though it works best in a party with a channeler or resto who doesn't mind you eating his spirits constantly with siphon(or if you can keep your guys alive take SoS yourself just to have a big AoE burst heal, condition removal, and 3 guys you can siphon yourself). It also adds to the healing and condition removal of the party(spirit's gift is freaking awesome especially with SoS), and unlike SY! works really well VS E-Burn and other mesmer stuff in Vabbi or VS mursaat.

Keep spirit's gift up, it's one of the best skills to use with spirit spamming(it will heal spirits and allies, so new spirits heal the older ones as you summon them),
cast shelter,
siphon it immediately,
side step(so you can siphon the new spirit, dropping them all in the same place only lets you siphon the original),
cast union,
siphon,
use summon if need be(try and set up before combat, but, you may have to summon spam during set up, just be sure to position yourself in a place to siphon a fresh spirit)
side step,
cast displacement,
siphon,
armor of unfeeling,
summon, then siphon+summon spam till they die and need to be replaced(this is actually the most energy intensive part, spamming summon that is. Make sure to use a staff or something like a kaolin wand, the mallyx rit greens or Stygian scepter so you get HCT/HSR bonuses for generic spells like summon spirits).

I've used this in a few HM missions where there were already offensive channelers or communers but no SY! and generally people were impressed with the damage reduction and healing. I got whacked by a boss spike hit once in a mission, and we almost wiped, but they got me back up and the damage stopped again.