I think as right now more than 1/3 of your cards enable Synthesis, some without costing extra mana, this is rather on the good side. I mean getting a Watchwolf distributed among three bodys for and the condition that I do something that's basically the essence of what the set does, seems very powerful.

I'd look at Lingering Souls knowing how powerful it is and suggest 1WW with 2 tokens normally and 4 for synthesis, if you want to push the card. If not, I'd still say 2 or 3 tokens but for 2W OR 1 or 3 tokens for 1W.

Edit: Making the assumption here that tokens are at least somewhat useful in your set. If you go low on playable anthem effects, don't plan to have team-buffing at a higher powerlevel and won't build any good and fairly cheap equipment to go with the tokens you might as well be fine as it is.

agree with all your concerns, trust me they're on my radar. but power balance issues are something i'm planning on addressing later down the track (unless they're really glaring, like Krosan Explorer was). they really feel like the sort of thing that playtesting will solve, rather than me trying to solve it now with no real understanding of just how strong synthesis is within the confines of the set.

and WRT effects that buff tokens, i haven't really considered if that will be around or not but i wouldn't expect to see anything below rare that has that sort of effect.