Congratulations! Your RIPPER evolved into RAVENER!
I really, really like Andilus' suggestion. It might not make quite as much sense in some ways (there's more fluff suggesting Rippers are larvae than that they can reproduce), but there's fewer balance concerns and it has a rules precedent (Parasite of Mortrex).
Deadshot, if you're keen on the 'growing up' aspect, there needs to be more balances to avoid Guard and suchlike drowning in cheap Carnifexes sooner than you can say '4ed Nidzilla'.
Suggestions:
- Rippers must commit to being 'X larvae' pre-game. If they're Trygon larvae, they can't take advantage of an opportunity to spawn a single Termagant to flit away and claim an objective.
- Sky-slashers must grow up into some sort of Winged creatures.
- As opposed to instant growth, a pupa stage is specifically mentioned in the fluff. Pupating is not something that can be done in the middle of a brawl! This comes to mind:
When consolidating after winning a
CC, a Ripper unit may attempt to pupate. The success of this depends on having Biomass available! The Tyranid player first decides how many permitted models, of what kind, they wish to spawn; the number of models to spawn may not exceed the number of W remaining on the ripper unit. The Tyranid player rolls a
D6 for every Wound lost by either side in the
CC (except for wounds lost to Instant Death - these attacks don't leave anything for the rippers to eat! The W lost by models that have been killed by Sweeping Advance do count, though), whilst their opponent counts how many Wounds the spawned unit(s) would have and rolls this many dice. If the Tyranid player rolls more 6's, the Rippers pupate! The Ripper unit loses 1W for each model in the unit they are spawning (no saves or
FNP apply), and a Mycetic Spore model is placed for each unit they are spawning, representing the cocoon.
At the start of each subsequent Tyranid turn, roll a
D6 for each such cocoon still in play. If it scores more than the individual unit member's W characteristic (or a natural 6), the unit spawns exactly as if the Mycetic spore had entering play that turn with the unit inside.
eg
Ten Ripper Swarm bases are locked in combat with 30
IG conscripts. The Rippers inflict 10 wounds and has suffered 6 wounds from the Conscripts. The Conscripts flee. The Tyranid player decides to spawn a unit of two Carnifexes! The Guard player rolls 8D6 - 1 for each Carnifex W - and the Tyranid player rolls 16D6 - 1 for each dead body to nom. The bugs roll more 6's, and spawn a MS cocoon, and inflict 2W on the Rippers.
Every turn, the Tyranid player has to roll a 5+ for the Carnifexes to pop out to play. First roll is a 3, not enough; the
IG pop the cocoon with a Krak missile, and the spawning is prevented. Should've made Hormagaunts, greedy!
This places more barriers in the way for players trying to get free Tervigons etc. Food for thought (pun intended)