First night.
According to new information, Rudy is not Galio, not Kog'Maw, not Sion, not Kassadin. Then he could be:
Poppy, Teemo, Karma, Malzahar (a member of the first-night blocker team), Katarina, Swain, Twitch.
The probability of being a negative role is 3/8, and if he throws a block on his own, it's 1/4.
But there's a very important factor: the doctor hasn't acted twice. Coincidence? Unlikely.
He has a 66% chance of ignoring blocks, defenses, and healing.

Барон "Vampires"
Отдай свои прошлые сны,
В сомненьях себя обрети,
В бешеном танце душа кружится!
Не думай, что будет потом,
Здесь и сейчас мы живем,
Стань хоть на миг сам собой, слышишь!