FŐNI = TO BOIL, TO BE COOKED
Indef.: főjön, főjenek
Def.: fője, főjék

Főni makes sense only in 3rd PS and 3rd PP!

VERBS IN D
They take one -D in imperative mood definite conjugation 2nd PS!
fed > fedd; ad > add; mond > mondd; tagad > tagadd; enged > engedd

VERBS IN T WITH A SHORT VOWEL
They take double -SS in imperative mood in all numbers/persons for both definite and indefinite conjugation!

Examples in 2nd PS indefinite:
fut > fuss; üt > üss; nevet > nevess; kutat > kutass

MONOSYLLABIC VERBS WITH A LONG VOWEL OR IN TWO CONSONANTS (if the last consonant is T)
They take -TS for imperative mood for all numbers/persons, in both definite and indefinite conjugation! The TS is spelled like double CCS in speech. Exception to this rule is LÁT which is a regular Group 1 verb!

Examples in 2nd PS indefinite:
fűt > fűts; műt > műts; ejt > ejts; gyújt > gyújts

As for conjugating verbs, we’re finished with imperative mood.