A leocrotta is a very fast, hard-hitting monster that can easily maul a mid- or low-level player. Often appearing before a character can be fully prepared, they're a common cause of death.
Low-level characters, especially those that don't specialize in attacks, are well advised to escape using any means possible. Strong ranged attacks are helpful but leocrottas are very fast and may be able to close the gap before they can be put down. Leocrottas respect Elbereth so engraving or burning that can be effective.
Leocrottas have no resistances so wands of cold, fire and lightning can kill them very quickly. As with the other quadrupeds, putting a leocrotta to sleep is an effective tactic if you have the means to do so.
If you're forced into melee combat with a leocrotta, a high damage weapon and decent AC is prefered. Because leocrottas get so many attacks per turn a small improvement in AC can give a big reduction in damage taken. Fighting from the stairs and walking to a different level to escape and heal is a good idea.
The leocrotta is derived from the Dungeons and Dragons Leucrotta, itself derived from the crocotta (or corocotta, crocuta, leucrocotta) of Indian/Ethiopian folklore.
The folkloric crocotta is a kind of evil dog/wolf/hyena, while the D&D leucrotta is an evil, ugly mix of a stag, lion, and badger, having a lion's body, badger's head, and stag's cloven-hoofed legs.
When #chatted to, like the Aleax, "The leocrotta imitates you." In ancient myth, the leucrocotta could simulate speech to call shepherds by their names to ambush them.
... the leucrocotta, a wild beast of extraordinary swiftness,
the size of the wild ass, with the legs of a Stag, the neck,
tail, and breast of a lion, the head of a badger, a cloven
hoof, the mouth slit up as far as the ears, and one continuous
bone instead of teeth; it is said, too, that this animal can
imitate the human voice.