Right - TBonne eats up any sloppiness on the part of Magnus. Morrigan’s really quick, so while Magnus positions himself in the air for his drop-down dash into combo attempt, she can dash and reorient herself and drop TBonne where appropriate.
Vs. Sent is harder if you get pinned down. If you can get into the air, her air fireballs can give you space, and you’ll usually hit Sent with at least a couple of those per match if he doesn’t wave-dash underneath. If he wave-dashes, you’re likely looking at air-dashing yourself to the other side of the screen and starting over. Her air dragon punch (and ground too, although you’ll likely want to stick with the quicker recovery you get from the jab version) help knock down Sentinels that get too close. Basically… if they’re in the air, you’ve got to knock them down because otherwise you’re in trouble (as always with Sent). As such, I usually use either Cable (preferred) or CapCom as character #2 for their AAA against Sent. Once you’ve knocked him down, you can dash and go for the TBonne cross-up.
Storm hasn’t been that popular of late, but I haven’t had much trouble with the few Storms I’ve played against (generally pretty good ones). Again, her low health makes her really vulnerable to the Morrigan (air-)dash/TBonne cross-over - if you do the down-swooping air-dash with TBonne cover, you’re pretty much covered. Run-away Storm has been a problem so far, and that’s where I’ve been switching to my MegaMan team.