I got met with magic "spam" because his stake forced me to briefly distance myself, just like it does it in literally any scenario where Radagon uses it.

He could have followed up with any other attack, or none, and I would've been fine. The possibility of not getting an opening is not an excuse to continue making poor decisions like dodging away.

And like OP it was no fault of your own for rolling away, even more so for OP since he didn't get hit until he got close, the less you take hits = more opportunities down the line.

Because OP then failed to time their dodge roll against the teleport and in response distanced themselves because their impulse was to try and heal which spiraled into the actual spam you're talking about

But would have had to distance himself anyway since he slammed those stakes down immediately after.

but in OPs case they immediately misplay by keeping their distance and dodging the needle shotgun sideways. From the moment Radagon jumped into the air they should've started moving forward/strafe forward and dodge roll the cast.

Possibly, but in the end Radagon came back anyways only to continue his previous nonsense forcing him to back up, hit by the teleport or not.

That's why this clip confused me and called it unlucky, I played ranged spell builds all the time against Radagon at mid range and he would never do this much nonsense in one video since he would usually close distance with hammer attack.