na-adjective
fantastic; magical; fairytale-like
Describes something dreamlike, enchanting, or otherworldly, often with a sense of beauty and wonder. Used for scenery, atmosphere, art, and stories.
その映画の幻想的な世界観に引き込まれた。
I was drawn into the movie's fantastical world.
The forest at night was wrapped in a magical atmosphere.
ファンタジック is a loanword often used for works of fantasy or whimsical design, while 幻想的 can describe natural scenes and abstract atmospheres as well.
Compound of 幻想 (fantasy, illusion) + 的 (-like, -tic). The suffix 的 forms adjectival nouns from nouns, giving the meaning 'fantasy-like' or 'fantastical'.