During our campaign this weekend we encountered an Ettin named Oinkers Boinkers. It had two heads (one head was Oinkers, the other was Boinkers), each with a different personality and it acted like two creatures in one body.
A sorcerer can twin a single-target spell to hit a second target that is different from the first target.
Legally, a basic Ettin is one target, I think, but the fact that I could say "I'm targeting Oinkers" or "I'm targeting Boinkers" suggests that there are two implied targets and a sorcerer could legally twin an attack spell to hit both heads but for their shared health pool.
Could a sorcerer act in this way?
Best Answer
No, Twinned Spell requires two separate creatures
The Twinned Spell metamagic (PHB, p. 102) says:
An ettin is one creature; just because it has two heads, it does not count as two creatures, even if the creature has two heads, two separate names and two personalities. RAW, Twinned Spell would not allow a spell to target the ettin twice.
This is further supported by reading the description of the ettin in the Monster Manual (p. 132):