Mag was my initial Warframe (Will replace with get Banshee when I can) & I mainly used Pull & Bullet Attractor. Pull for Dealing with multiple enemies. Especially Grineers, hate their armors, & Bullet Attractor against bosses.
Btw, there was something funny that happened to me once while playing. I used bullet Attractor on one of those Grineers that wielded a HMG, (you know, a minigun that gains Fire Rate over time) & it caused the Grineer to hit itself XD I mean, it's as if the Bullet attractor reflected bullets right back at the Grineer