ok got a few questions

1, ok i found a key, it leads to a battlefield,
i clicked on the key which said i unlocked the battlefield but diddnt take it with me
i dont know how to get ot the battlefield, i press escapte the enter battlefield is greyed out


2, im at the part now, (i couldnt really kill anything dual warrior from up the point were the gargoles are, not enough health potions) were im supposed ot hide from these death nights, but there dosent seem to be any way to hide from them,

any help?