He Almost Killed Me…

In English, when something almost happens, we tend to use the past tense, even though the action was not technically completed:

1.  He almost cried.

2.  I almost fell down.

A similar construction exists in Spanish, using the word casi, but strangely (to my ears anyway) often using the present tense.  The above sentences become:

1.  Él casi llora.
2.  Casi me caigo.

After a tough battle with someone with magic rings, Iron Man ponders:

"He almost killed me with only 5 rings.
What would have happened if he had possessed all of them?

Notes:

the conditional perfect tense:

ha ocurrido→habría ocurrido

redundant object pronoun:
de tenerlos todos
the de here is an abbreviation of en caso de