The best replacement for allusion is illusion.

The best alternatives to allusion are rated as following:
★★★★★  illusion
★★★★  reference
★★★  allegory
★★  metaphor
★★  analogy
★  simile
★  symbol
★  apostrophe
  anecdote
  symbolism
  antonomasia

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Speaking about allusion, one probably shouldn't forget about examples.

Other search terms related to allusion and their ratings are:
★★★★★ examples
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