I agree - I run across Indos at L29 or even L30; you can afford to keep Magna in as long as you save it “for when the time is right”; its certainly not an opener when underlevelled.
Draco is another connundrum - ignoring the “moral” arguments (plenty of threads on those) I found it as much a hinderance as an asset to the team; I did use it, but now its on the bench even at L28 - I save it for strike towers.
Using Draco alongside hit and run creatures (in my opinion) causes more problems than it solves - like you I have Erlidom and Dilorach; and often use Tuomoloch. The problem arises if it ends up the creature you run into (either in the initial pick or through creature deaths); yes - if you get a hit and run into a swap in, it can be great but I find with Dilorach and Erlidom the hit usually delivers the killer blow - so you are left with Draco swapping in and just standing there with its pants round its ankles looking stupid. I found there were too many times either this happened because I forget to check or I had to pick a different sub-optimal move for Erlidom or Dilorach.
Its bad enough raging at another player because Draco ruined the battle - its another level altogether raging against your own team …
I’m stockpiling Dimetrodon for an Irritator event (just watch that become rare as soon as there is one) and planning on boosting Magna with stat boosts.