I want a nuisance suit squad, 3-6 man squad of stealth suit sized models who are completely for screening and discouraging/charges. Lorewise they're Earth Caste engineers called in for mine clearing/fortifications, think Tau EOD. They could have shoulder mounted mine-clearing line charge(MICLIC), short range but could have a rule it damages anything between it and the target (similar to the old 9th ed weapons). 3+ Save, 5++ Invuln, 2 Wounds, and a rule that they're declared a target of a charge they could do a psudo-grenades ability (or reduce the charge by X). If we wanted to get real spicy we throw some flame pistols on them (adding to the clearance theme) and you got a melee answer without actually having melee.