When to face Diablo?

[Bob the Beholder]

And when you are going toe to toe with him, would you use cobra for the leech, or tiger for the extra damage?  I'm leaning towards tiger.  Hopefully I can hit him frequently enough that I dont lose all the charges.  LOL

My opinion, you should use 'em both. Though you won't be hitting as often as you like (he's got something like 57 percent chance to block all physical attacks, if I remember correctly), the chance that you'll hit with both of them in effect isn't too bad. Even if one wears off, you'll likely have the other still on there.