I think refusing to stay dead is the most Mastery thing that Simms brought to the Master.
I loved the Master during the RTD run. I watched and re-watched him wipe out his Cabinet and wheeling the aged 10th Doctor around. I could barely breath for laughing.
I've always loved the Master. I'm always slightly puzzled when people complain about the lack of consistency in the character since it's been fairly standard since Ainley was playing him. Everyone talks about the campiness of Ainley's Master, but it's the version from Planet of Fire and Survival that I always remember. Would that we had more of that sinister vibe during the 80s.
As luck would have it we're watching The End of Time as a family tonight, so this has set the tone nicely.