Doesn't WotC ususally do
Sharer of Souls
Enchantment Creature
Other creatures you control get +1/+1.
1/1?

Yes. That's the point, to make it feel like an enchantment creature. What's more enchantmenty than not having toughness?

Also, Wizards doesn't usually do enchantment creatures. ;)

In most cases 'Lords' say "All other creatures" because people have a tendency to forget to count the Lord anyhow. In this case, I think people would have a hard time forgetting to count the Sharer of Souls. If we changed its p/t to anything else, though, I think we'd have to go with "all other".

I like it, very alien feeling, I can just see what craziness xcan happen with four of these in play - 16/16 P/T for 8x ? Yes Please!

Er, four of these would just all be 4/4s. If it's only affecting copies of itself then it's inferior to Wizened Cenn. But it's a lot more versatile than the Cenn, obviously.

I really like this design. Its deliberate disconcertingness works very well: classless creature, 0/0, uncommon Glorious Anthem effect like on Kabira Vindicator. Nice one.

I think Camruth meant there would be 16 total power and toughness.

D'oh. Yes, of course.