So suppose you had 3 of these in play (unupped).
You would activate the ability and then all your
producing creatures would provide 1 point of healing to you and any creatures that are in a slot next to them.
E.g. if you had 5 fire producers you would heal 3*5=15 points.
(note: you could always click cancel if you only want the healing but dont want to overwrite an existing ability with fire production)
This differes from upped version in 2 ways.
1) it has to be activated each turn to get the healing effect
2) it stacks (so the upped version would be providing 2 healing per fire producer regardless of stack size)
This should encourage people to use both upped and unupped versions in their decks.
The mixture will depend on whether they are after just raw healing or light production and healing.
I like this. Reminds me a lot of firefly, and even synergizes accordingly with the upgrades. It's also a cool theme. It does sort of overshadow empathic bond, but it adds quite a twist.
Ya, if you get enough of these in play they could overshadow empathic bond a little bit, but it would at least take several turns to get "fire" spammed to all your creatures to do so. Hopefully that will keep it in a sufficiently different niche.