For this you need to complete any challenge on the planet Torval without taking damage. This is easier in challenge mode with the Harbinger/Mega Supernova. Easiest challenge by far is Blast of Fresh Air, there are two landstalker turrets in this challenge so make sure the use the EMP ability on them.
Play the challenge as normal by using your bots to plant explosives onto the statue. Be weary though more enemies will spawn when you place the explosives. Keep using the Harbinger and you'll get this no problem.