I've been messing around with the 1.17 Alpha for a bit, and I think the soul effects are really cool! I thought of some suggestions and neat features/changes, which I think can make them even better.

• Penance IV could kick demon & wandering spirit players out of their bodies, essentially making a "zone" where they can only be souls around an obelisk. Perhaps shells left behind would autowalk away from an obelisk that produces it, so the shell isn't irretrievable after that.
• Making Emancipation a leveled effect, where level 1 simply lets requiem players fracture, and only able to inhabit the undead and shells, level 2 means they can inhabit creatures made soulless by taking their soul with a soul vessel, and level 3 means they can inhabit any creature, but cannot control things that have souls, simply seeing through their eyes as if they were in spectator mode. Using the "spectator" feature on another player might work better if it were locked to level 4, or perhaps there could be some kind of indicator on the possessed player that they are being seen through, maybe a colored vignette on their screen, or a subtle change in vision tint.
• Some kind of stealth effect that makes souls totally invisible, rather than the shadowy dark figure they normally are. Perhaps this could be balanced with making them not able to move through more blocks, or not able to fly, or making the passthrough effect extra obvious. This effect I think could be called "Secrecy".
• A soul effect that makes you resistant to the effects of an Obelisk. With Penance and Attrition as obelisk effects, it would work really well as a defensive measure against requiem players to have obelisks surrounding your base that debilitate them. However, this would also effect your own soul if you were a requiem player. With this effect, however, you would be resistant to all Obelisk effects for a short time, both positive and negative. I think this effect could be called "Defiance" or "Impedance".
• Finally, a soul effect that makes it easier for soul players to move through blocks. I think it makes a lot of sense that requiem players are limited in speed from moving and flying through blocks, but I also like the idea that inside their own bases, the ability to freely move through the physical world makes for more possibilities for building away from the limits of needing doors. This could be a leveled effect, with each level making you slightly better at moving through blocks, until level IV, where there is no resistance. Once at level IV, Obsidian becomes traversable, but with the very slow passthrough normally experienced when requiem players try to move through blocks. This effect could be called something like "Abstraction", or "Freedom".

Penance IV could kick demon & wandering spirit players out of their bodies, essentially making a "zone" where they can only be souls around an obelisk.
That should already be the case. The shell walking out is an interesting idea we didn't think of though.

Leveled Emancipation could work, but we always want soulless creatures to be possessable, no matter the level for it, so I'm not really keen on that idea. Keep in mind emancipation also needs to be able to be used with Ichor Vessels, that are gated to level one (at least for the moment). The spectator suggestion is very cool however and could make sense.

Secrecy could be an interesting effect, kind of an Invisibility for souls, but we would have to be careful with how we add it to not make it overpowered indeed.

I don't think an effect against soul effects would work / be a good idea. We have some plans for a similar feature, but it wouldn't be a soul effect.

Finally, the lessen resistance effect would be interesting, and even more if leveled. But again, we would need to be weary about making it too powerful.