Few Questions (New Druid)
 

I've seen chanters break their charm by going invis. Not sure if this is very mana efficient, as i've also seen them cast some spell that looks like a nuke which seems to breaks charm.

Zeonick was likely seeing some form of dispell.
As a Druid you should use the Hide skill to break your charm. And, you are correct; You won't be too gear dependent charming.

interesting! didnt know using hide would break charm. but then again i am a noob.

.. I think it is interesting that you have characters on the server Dnice, and both are porter types.

If you don't have Hide, you can use Invisibility Versus Animals, which is a pretty cheap spell. You're right, charming does not require gear.

Any idea why my charm is breaking like 5 - 10 sec's on dark blues? Does it have something to do with my cha rating or just bad luck?

Nothing to do with CHA. Charm duration for druids is based on MR and monster level. You should target dark blues that are as close to light blue as possible - high dark blues will partial resist a lot more.

Thanks again

Hide hardly ever works. It's just not worth it to chance. Just put invis vs animals in a spell slot then make a hotkey to target yourself and cast that spell slot. The way I do it is snare two mobs, charm one, turn on taunt + attack, run in a circle until they are fighting each other, med. If charm breaks... repeat. If one mob gets to 20% hit your invis button.