dispell (third-person singular simple present dispells, present participle dispelling, simple past and past participle dispelled)
In modern standard spelling, *dispell is a misspelling of dispel. The doubled consonant of the correctly spelled inflected forms (dispelled, dispelling) probably influences the urge to spell the infinitive form with -ll, as does the word spell (spell, spelled, spelling), but dispel is like expel, impel, and propel regarding infinitive form. These words all share the /pel/ root that means to drive (in or out), push/pull, or beat on, with the prefixes indicating the type of driving/pushing (dis-, ex-, im-, pro-). Most major dictionaries do not enter *dispell because it is not used in modern standard spelling.