Hello, I'm trying to figure out wand of warding but all it seems to do is stay afloat for 1 turn before shooting a beam at an enemy and then subsequently dying. Am I using it right? Also, if I become a battlemage with it, what does it mean when the wiki says that it will "Heals all sentries on current depth. More advanced sentries get healed more." How is is supposed to heal something that dies in 1 turn and also I haven't seen these "advanced sentries" either. Please help!
It consumes its health pool to shoot. It only has enough health for one shot when you only put one zap. If you zap it again, it will grow and be able to sustain more than one shot; more zaps, more health and damage. You can upgrade the wand to get the crystal to a higher (more advanced) level doing more damage and sustaining more shots before dying: A wand+0 can support a crystal of level 2, +1 can support level 3, and so on. You can alternatively place more lower-level crystals (eg., a +2 wand could place 2 level 2 crystal sentries) and that's where "heals all on current depth" comes in. It's dying in one turn and not advanced because you haven't invested more than one zap on it. The whole idea with this wand is that you're investing turns spent zapping up front to get that time/turn investment back in the form of damage, sort of like an action-economy battery.
If you want a turn of aggro, or, in fact, five turns of not being hit, just use a transfusion wand. Or use a wand of blasting and get rid of them. Or corrosion and let them melt. But that thing just dies in one thing the second you enter the prison. It's useless, it doesn't even deal big damage, and the armor is only 50% of all your received damage, and breaks very fast.
Maybe you haven't leveled one up enough. It's good. Lots of people place it in S tier. It's OK if you just don't like it, but calling it bad is disingenuous.