Means of gaining a grow token:
1) (Growing Neph) Grim feast (bonus action - so Once per activation)
2) Black blood shaman - Ancient Ritual (Models affected once per turn, TOTS ONLY)
3) Vasilisa - Pull the strings can give 1 model 1 bonus action eg Grim Feast
4a) Nekima2 Only the Strong survive - vicious Vitality trigger (Once per turn)
4b) Nekima1 Hurl Corpse - Fast food trigger (Could give 3 grow tokens to 1 model - but it doesn't generate any corpses and each one does min 2 damage)
5) (Growing Neph) Relish in blood (kill a higher cost model)
5b) (Young/Mature Neph, Nekima1) Meat for the young (another model kills with a trigger and lets another model trigger Relish)
You can theoretically do the top 4 turn 1 to grow a tot into a Mature!