"From a lion" or "from a lion" - how to write and speak correctly?
The use of the preposition oto (and in this case it is so correct) is not considered vernacular in all cases. It is quite justifiably used before words beginning with certain groups of consonants: day by day, from everyone, from flax, from ice, from sleep. Those. we see that these are, most often, words starting with several consecutive consonants in a certain combination. You just need to remember such cases: from flax, but from an explosion, from a splash, from fear.
In Russian, there are paired forms of prepositions, differing for full accord in some cases only by the appearance of a fluent vowel o, for example. Above Above, the sky is blue, about - All people will say about me, etc. As for the pair from - oto, combinations with the preposition oto are less common, since “oto” is used only before certain groups of consonants: from sleep, from everyone, from day to day, etc. So in your example it would be correct to say: Move away from a lion !, because the preposition "fromo" is just used before the combination of l (from ice, from flax, etc.).