Does Master of Cruelties survive being blocked by a creature with 4 or more power?
Generally speaking, the Master will survive the battle; the first strike/deathtouch combo is that powerful (but appropriate for a 5 mana multicolor card). First strike will make sure the Master deals combat before creatures without this ability; with deathtouch, even a single damage is enough to kill a creature. In the 'regular' combat damage step, when the blocker would deal damage, it's already dead.

Some exceptions are when the blocker has first strike as well (or double strike), or when it has protection from black or from red. In the first case both creatures die, in the second case only the Master.