my prob with inferno is mobs that you simply cant get away from, those fing frog like things in act 1 that leap/ naturally run fast, how the f do you keep them away from you to do any damage, yea as a wiz i can run/telly around and let my hydra kill them for 10 min, but the moment i stop to cast anything there is a near 50/50 chance i get 1 shot, i think its more lke 90% on my DH
What I hate the most about them and the Lacuni as well, is the fact that if they jump at you then you actually have to wait until the jumping and landing animations finish playing before any hits you land on them can register. I mean it as a Barbarian player but I guess it's the same with other classes. I do have other classes but I can't remember if that problem is the exact same with my own Monk and my DH, I'd have to check again, but I'd guess the situation is the same for all classes. And those frog-like creatures you speak of (forget their name), they have their unique ability (and animation) when they burrow underground, but if for example you try to hit them with any attack WHILE they start their burrowing animation (even though they are NOT entirely burrowed underground yet) you pretty much miss all the time until they get back to the surface.
Additionally, the same applies for that bigger Lacuni variant, the one that duel-wields katanas or something and does that combo-like animation attack, during that animation they're invulnerable even if visually you did hit them, not to mention that if I'm not mistaken that animation cannot be interrupted by the player or any attacks, once it starts, it plays out completely, and if the mob "had to die" during the animation then the animation still plays out and the mob dies AFTER the animation is over. Another example of animations having to play out entirely before the player can actually damage the mob are some zombies in the Halls of Agony, those that come from under some door frames with fire at the bottom, they crawl on the ground to stand up, that animation makes them invulnerable even if on-screen your swings or your spells (or arrows, or whatever you throw at them) "hit" them physically.
In other words, if you move your cursor on them while that animation plays out you have no actual target to hit, even though the animation of your own attacks would visually hit them. One last example I can think of by heart (I know there's others), those giant bat-like winged creatures in Act III, flying demon thingies, their landing animation needs to be played completely before your hits can register on them.
That, honestly, pisses me off.