This mod aims to fill in the gaps of the categories not covered by the vanilla units.
Specialize in healing and unit factories. (T2 produces monos, T3 produces monos, T4 produces polys/flares, T5 produces flares/polys)
Rana -> Renidae -> Protidae -> Renigata -> Urodela
Possibly snipers. T2, 4, and 5 will sap. Maybe a unit factory T3 that produces needle. T5 will definetely produce needle.
Speed.
Specialize in speed and energy.
Needle -> Dart -> Spear -> Javelin -> Harpoon