I didn't get involved in the playtesting but am having fun with the new Basic Rules (creating my own bits of stuff based on it) and the Starter Set (playing online, having a ball).
With the bits of creative stuff I'm messing around with, I'm converting over an old 3.5 adventure I (semi-)wrote to 5e. I was looking at converting over the 3.5 Darkmantle and Grimlock stat blocks in two of the dungeon locations to 5e but am struggling with their Blindsight ability.
3.5 states that they are immune to such things as gaze attacks, illusions, etc. However, the 5e monster stat blocks in the Starter set seem to note Condition immunities (I'm thinking blinded (+ charmed for the Darkmantles)), Damage vulnerabilities (I'm thinking Thunder) but none of the Damage types for Damage immunities seem to cover an immunity to visual attack forms and none of the Starter set creatures seem to have Blindsight.
How was this handled in the playtest rules and/or has anyone any suggestions for how it's most likely to be handled for the MM?
A creature with blindsight can perceive its surroundings without relying on sight. So anything that require to ''see'' or otherwise rely on sight doesn't affect them, such as gazes attacks or blur spell. The monsters statblocks may also contain additional immunities that relates to that.
BR65 Blindsight: A creature with blindsight can perceive its surroundings without relying on sight, within a specific radius. Creatures without eyes, such as oozes, and creatures with echolocation or heightened senses, such as bats and true dragons, have this sense.
So, just to be clear: you're saying that the 5e statblock no longer needs to state that a creature with blindsight is immune to (say) gaze attacks because merely including the blindsight annotation in the 'Senses' section includes that assumption? The only necessity is to mention related damage type immunities and vulnerabilities and/or Condition immunities?
Yes, in the Starter Set for exemple the giant spider has blindsight 10 ft. with no immunities. So a spider that would close its eyes and thus strictly rely on its blindsight sense would be unaffected by a gaze attack or blur spell basically as they are abilities requiring you to see. But that doesn't make the giant necessarily immuned to gaze attacks because it can also see with its eyes.
Aha! I didn't even notice the spider had blindsight. Great - thanks for the help.
My pleasure you're welcome! 