I came across this post from croupier at codemasters, I'm going to copy it in full below (in compliance with creative commons license) because I just think it's a very good read for minstrels (and a lot of companys would rather block codemasters than blogger ;-)).
I've tried to answer a few most common questions regarding minstrel's work in PvMP.
1. I'm dead, why the minstrel doesn't resurrect me?
Few possible reasons:
a) Our combat resurrect skill (from a legendary trait) has a cooldown of 10 mins. If we used it, we need to get out of combat first, to res you.
b) You are too close to creeps. Our res skills have range of 25m.
c) In tight situations (fighting a tyrant or a large group of creeps) we don't have time to res if we need to heal others. Resurrection skills have a long casting time.
2. If I spam chat with "rez plz", "I'm dead!", "need res!!1one" or send a tell to a minstrel will I get resurrected faster?
3. I died! Why didn't I get a heal?
Few possible reasons:
a) No "line of sight". Any small rock, fence, trunk, wall, tree can cause this. Please stay in line of sight.
b) Minstrels can't heal while moving. If you charge or chase a creep - we have to run too. If we run, we can't heal. If you need a heal, stop or even better - fall back a little.
c) There are creeps/npcs attacking a minstrel. Every hit we take makes our casting time longer, even to the point we can't heal at all.
d) We are stunned/silenced. Creeps who know what they do, stun/silence us a lot.
4. How can I protect minstrels?
a) Watch our health. If we are taking damage defend us.
b) If we take damage from NPC try to get his agro. Leaving untagged archers and other NPCs around, will result in minstrels getting their agro.
c) If you see that creeps are on a minstrel, try to root, slow or stun them. If you can heal us - do so please. When creeps attack us it's really hard or sometimes impossible to heal ourselves.
d) Try not to leave us behind. If you do - wargs will kill us in seconds. If we are webbed or stunned wait for us. If you order a tactical fall-back, wait for us to finish our heal or resurrect spells.
e) Try to use your class specific protection skills on minstrels. Don't save them for later or "just in case". We use all our skills and abilities to protect you, often paying with our lives. We expect that you back us up too, if needed.
5. Can minstrels blind NPCs?
We have a skill "Song of Distraction" that reduces NPC's perception by 75%. NPC's can resist it tho (~15% chance from my experience). If they do, they will agro. You can tell that a target is distracted by a black-red debuff icon.
Example: We use "blind" on a Chieftain. Now that Chieftain won't agro, even if a Tyrant is pulled.
Example2: There is only a Tyrant left but there are many creeps hiding behind him, ready to defend him. We "blind" a Tyrant. Now you can move much closer (to 25% of his normal agro range) to him, or go around and nail the hiding creeps before pulling a Tyrant.
6. Omg, wtf? Why that minstrel keeps stealing my kills? Shouldn't he stick to healing?
Minstrels are the only class that can efficiently and constantly damage an opponent from range, while running. That's why we sometimes get killing blows while chasing a creep. For 10k+ kills I got only 230 killing blows tho.
7. How can I thank a minstrel for a great healing?
No need to thank us really. Every class does his job.
But if you really need to - give him some ale. Or a pie. Or both. ;)