ADJ

lengthy, long, prolonged
brief, short
5-minute, 10-day, etc.
good
bad
He's going through a bit of a bad spell at the moment
quiet
barren, lean
Viera ended his barren spell with a goal against Parma
cold, dry, hot, mild, sunny, warm, wet

VERB + SPELL

go through, have

PREP

during a … ~
She managed to write a letter during a quiet spell at work
~ as
He had a brief spell as ambassador to Turkey

PHRASES

a spell of … weather
a spell of sunny weather
a spell of unemployment

ADJ

magic, magical
powerful
hypnotic
the hypnotic spell of the crickets singing in the garden

VERB + SPELL

be/come/fall under
cast, put, weave
The witch cast a spell on/over them
break, remove
She uttered the magic word, and the spell was broken

PREP

under a/the ~
Sleeping Beauty was under a spell when the prince found her
under sb's ~
The audience was completely under his spell