'Cthulhu', if you don't want to go to the effort of pronouncing it close to right (as in freebfrost's quote), in any case case has two syllables, not three. 'Cth' is a single complex consonant, not a syllable.
In 'Faerûn', the circumflex over the 'û' makes it a long 'u' sound, so Fay-roon...