You will start this test with all three points taken, they need to be neutralized and recaptured.
Optimal build - AoE with Overextended Mod (Frost, Excal, Saryn, Mirage, Rhino)
I used a frost build with overextended for max range, and duration mods. Power isn't important because they'll be trying to capture, not break your snow globe.
Start the mission, pop a Team energy restore, then rush to capture Point A. As you're capping, you should be picking enemies off with a hitscan weapon (I used a regular Soma) that are rushing to position themselves at B and C. Once youve captured, Immediately lay down a Snow Globe and repeat at the next capture point. After you've captured all three (It's better to cap a new point than rush to one in conflict) it's simply a matter of picking off Grineer spawns and neutralizing Conflicts.
You should win by a large % margin, hope this helps.