As with the rest of Meter characters, Astronema's assist counters Mastodon Sentry's counter really well, but he still has ways to recover his points fast. If he activates the Counter, then the best thing to do is to avoid, interrupt or block the attack, as he still gets points even with the Counter mode (1 for Door Breach, 1 for the Grenade Toss, 2 for Focus Fire, and 3 for the Riffle-butt Smash) The assist though it's very good for escaping, will really help many close range Leaders in their combo game