You have come to test with other types of attack (spells for example)
What? Spells?
Iron Skin blocks physical…
U still vulnerable to debuff as stun that cancel the skill.
I still don’t understand how to use iron skin~~ I’m more of PVE type… rarely i use iron skin but when i use it… some range/magic mob attack and it cancelled…
with high DEX… dodge always been an issue to see iron skin in effect 
maybe I’ll try later on higher level map…
I still don´t see any use for it. At the beggining of the channeling it can be cancel, don ´t let you move and is a smaller, weaker and (for now) has a longer cooldown… totally worthless in comparison of much usefull skills like Safety Zone, Revive, Carve World Tree , Ausrine or even Fade.
In PvP I wouldn´t use it at all and Pve just as a filler for the other skills cooldown.
In PvP, you use it to activate and reflect enemy pears