I don't like all the clever-clever titles being proposed because (1) they probably restrict the audience and (2) one of the difficulties MIRI faces is persuading people to take the risk seriously in the first place -- which will not be helped by a title that's flippant, or science-fiction-y, or overblown, or just plain confusing.

You don't need "primer" or anything like it in the title; if the book has a fairly general title, and is short, and has a preface that begins "This book is an introduction to the risks posed by artificial intelligence" or something, you're done. (No harm in having something like "primer" or "introduction" in the title, if that turns out to make a good title.)

Spell out "artificial intelligence". (Or use some other broadly equivalent term.)

I would suggest simply "Risks of artificial intelligence" or maybe "Risks of machine intelligence" (matching MIRI's name).