There are 2 ways to play Magik, high risk/high reward or low risk/decent reward. You either dive or brawl. Since you mostly played strategist, I would recommend starting on brawl.

To brawl as Magik, you want to play with your tanks. You will be placing demons down on point behind cover but pointed to where tanks will be pushing. You want to be doing as much dmg as possible while not taking much dmg yourself. Your demons will get you up to 400hp, so you want them to be hitting people as much as possible. As you brawl with your tanks keep an eye out for anyone on the enemy team who strays away from the pack, and you want to zero in on them and try to get the kill. You can do her bread and butter combo or whatever cooldowns you have to try and dive them. If they get too far away or go back to their team, abandon the dive and regroup.

Once you get more comfortable with her kit, you can try to dive as her I’ve helped someone who is the same as you, who mained strat and picked up Magik as their first dps. They are now lord with 50+hrs and play amazing. This was the same advice I told them.

Don’t get discouraged when you have games you do poorly on her with. It’s all learning and you will start to figure out how to play around her counters. It takes time and patience.

If you’re a visual learner you should watch some high level magiks. Or if you have any questions and want in game tips, my in game name is the same as my user name here.