some languages, e.g. Java, require avoiding integer overflow, while others, e.g. C, do not.
the description does not warn about very large inputs.

A very wordy problem with a very simple solution. Consider rewriting the problem to make it more readable, free from punctuation and grammatical errors.

This is a really fun kata! I just think that the instructions could be a bit more clearer. Maybe include one or two examples in the Description?

Random tests can be 0,0, add this to test cases to add error handling or remove from random tests?

I found the instructions rather confusing, and am offering a potential revision/clarification:

"A hero is on his way to a castle to complete his mission but the castle is surrounded by powerful dragons!
If each dragon takes 2 bullets to be defeated, does our hero have enough ammunition?

Return true if he has enough bullets to survive."

Using assertEquals(true, ...) and assertEquals(false, ...) instead of assertTrue and assertFalse. Why??

I think the test cases in python should include Test.assert_equals(hero(0, 0), True) because some of the solutions posted would return that as False.

the castle is surrounded with a couple of powerful dragons

I would suggest changing "a couple" to a "a number"; a couple specifically refers to there being a small number and not a wide dynamic amount, so this description is misleading (and contrasts with the test cases).

show better fail messages not only "true" or "false"

Oh hey... I got a BASH Translation up: https://www.codewars.com/kumite/5bc1557b515f4e5dca000121?sel=5bc1557b515f4e5dca000121

Not certain how to do that fancy forum magic... does these comments use BBC Dialect? A Hitmel Dialect? A Wiki Dialect?