You have Rabbit or Wargling but lack a four-power source.
Consider Hunter before another conditional reward.
Its counter can establish the missing condition without another card.
Beorn is your early standout pick.
Favor useful early creatures and reliable green mana.
Beorn can turn existing creatures into Bears; you do not need to force black or reject every non-Bear.
The support is missing
Treat this as a flexible construction, not a compulsory named engine. Keep an early green rare while remaining open to another partner color.