:P I just got them both and tried them out, the skeleton summon is almost 100% chance, very often the first shot will summon one, it has a chance to summon another one but not immediately and only happens rarely. It has a chance to summon either a melee skeleton or a skeleton archer.
The skeletons can do damage unlike the WD mask, for me they hit for about 12k so its not too bad; they can die has health about same as inferno act I skeleton and in act IV they will die in one shot.
Skeleton summoned does not always follow you, they will follow whoever is closest to them at time of summon, and they are transparent rather like ghost :D.
I like the ring, mine gave me 5k dps boost, but they are not worth getting just because of the fun of proc.
Just did a bit more testing, the skeletons if not killed will be destroyed after about 20 secs, the summon seems to have a 20 secs cool down as well, but I have seem 2 skeletons out at same time before just not sure how.
They have low hp, can only take 3 hits from the zombies in act I (inferno), but they can critical on hit for about 20-25k (act I inferno).
Archer is best to be honest they shot rather often, once target is acquired. Also very important is that the skeletons has the same AI as the normal ones, monster needs to be fairly close to them in order to acquire target (about 30 yards); melee skeleton often just standing still forever even if a target is near, or just doing that laughing animations before its killed, they seems to attract monster attentions rather well.
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