I voted for dryad and oak guardian. Those two cards are meant to be together.
The other ideas are awesome too, but I think dryad fits in the theme of life very well in that it heals. It would makes sense for life to have renewable creature healing. The oak guardian can make dryad a little OP, but it takes two of them to help the dryad to survive a single ROF, so it's not that bad. They can be hard to set up, but REALLY hard to get rid of once set up. There's finally a counter to plague other than immortality. Gives life a little bit more strength against death, that makes sense too. I liked the sapling and the elder tree as well, but it seems quite UP IMO. The elder tree is okay, but the sapling is vulnerable in the beginning and become useless and hard to get rid of afterward. Alpha wolf is okay, but I can only vote for two cards. The tyrant lizard is almost ridiculously UP, it needs to devour a creature on your own side that possibly cost a few quanta to get a 2/1 boost in stat when forest spectre gains 2/2 for only 1 quanta and it absorbs 2 quanta per turn and will die if there are no food. They otyugh can devour enemy creature and it will not die if there are no food, so the tyrant lizard is very under powered. Killer bee nest is a good idea as well, but the continuous upkeep is a bit staggering, and I picked my 2 cards anyways.
P.S. Alpha wolf is a little OP, but it's not 9 damage, it's 7, but the pack wolf is definitely OP. The upgraded version costs nothing, play an alpha, then keep fractaling the pack wolves and you get insane creature spam.