The problem for a solo player is that you need the perfect circumstances to have a chance. The best way I found is to be losing badly, so that spawns 4 and 5 have plenty of weak adds then unleash your super, preferably one that extends on kills. Then hope that a helpful teammate doesn't shoot a rocket or throw a grenade into the middle of it....

Bottom tree sentinel with grenade tonic. Pop your super for unlimited shield throw. You're welcome. I've got 6 of them yesterday.

No they're not.