Call the sentients Trolls, yes?
Upgrades: All available (why the hell not)
Design the following:
ProtoGrowth: Fishtail leaves on top of roots. Nothing but a biomass-producing weed. (spam across your entire territory)
Mark II ProtoSoldiers: Take the BugLizard body plan (six legged lizard). Make it bipedal (use troll DNA). Give it Chitin, acid spray (scarabs, triffids), and chitin claws (combine troll claws with scarab chitin). Make it 1m tall.
Mark II ProtoGenerals: Upgrade their brain power with the Trolls' brains. Make them twice as big.
ProtoTank. Mark II ProtoDefender
Basically the ProtoDefender except scaled up so it is 6m long and 3m high. most likely an insane amout of Biomass, but it will easliy take out the sapients trolls. And anything else in it's way.
The new Mark II Line is the latest in Hive mind military bioengineering. Still prefaced with 'Proto', as they all remain prototypes for what is still to come (universal conquest), the Mark II line boasts an increased size to match the impressive girth of the native trolls. The soldiers, though still small in comparison to the trolls, are at least more than an irritant towards the trolls; sufficient numbers will be able to swarm over them with ease. The Generals have been doubled in size to remain larger than the soldiers, as well as having increased brain mass (courtesy of troll brain DNA).
The Mark II defender has been increased dramatically in size in order to pose a serious threat to the trolls; one defender should be able to tear a troll to pieces.