Adult Gobot

Power of Swarm: for each 2 Young Gobots/Adult Gobots nearby(10 ft) attack damage receive +1 (up to +5)

Underground Movement: Gobots are moving underground, something like 3-5 ft deep, because of what can't receive opportunity attacks(though,reactions still possible),mostly,still affected by AOE spells.

Sharp Teeth: When Adult Gobots get out of earth to attack, they most likely gonna bite legs. Attacked creature must make Constitution saving throw (15 or higher). When a creature fails, it lose 5 ft of moving for 2 rounds, stacks up to 15 ft. If saving throw is successful, as a reaction, Young Gobot can be attacked by another leg, instakilling it.

Weak Telepathic Bond: all Young Gobots and Adult Gobots connected to their summoner telepathically, but can understand only most primitive orders in 30 ft radius(attack,retreat,another target).Overall their mind is primitive,and,if DM want, they could be controlled not by summoner,but by DM himself.

Eyeless: since this creature doesn't have eyes,it can't be affected by any spells that affect vision or somehow use it.

Poisonous Gland: With adulating, because of many factors, Gobots grow a gland with poison,to catch bigger prey and turn it into rotten chunks of meat and bones. Target must make a Constitution saving throw(11 or higher). On fail, receiving 6(2d6) poison damage, and only one third(2) on a successful saving throw.

Bite.

Melee Weapon Attack. +2 to hit,+4 with successful stealth, reach 5 ft, one target. Hit 8(2d4+3)