When to cast Slows
 

I have my enchanter up to level 29. When should I cast Tepid Deeds? On easy mobs they die so quickly that it seems like a waste of mana. On hard mobs, the mob instantly aggros on me and does not go back to the tank until mob is under 50% health. And even cons or higher, I don't even bother casting cause it will get resisted 80% of the time and that is even with it tashed.

If the mob is dieing within a few seconds of slow landing, stop wasting the mana.
If you are ripping aggro off the tank by slowing, then you should have rooted the mob first.*
If you can't land slow, then you should have tashed and rooted it first.
If you still cannot land slow, then the camp you are at is too difficult for your level.

* If the tank is a knight and they are not casting their high aggro spell on the kill target, then you need to clarity/breeze them and then bitch at them for not making use of the unlimited mana.

If the has a weapon that procs, you are usually pretty safe casting it after it does.

Distance also plays a role. The farther you are when you cast spells, the less likely a mob is going to beeline to you because of a slow.

Another alternative if you don't have a heavy caster group is to root the mob and have the tank use proximity agro. This is assuming the melee in your group understand that a rooted mob hits the closest thing to it.

all you have to do is make a game out of it!

Pick a number like, 80.. Slow when mob gets to that %.. Then take note of what % it's at when it lands, if it seemed worth it (how many hp did you save the tank in the time it was slowed.. Maths.. Compare to mana cost and rate of heals etc) the try to +/- the 80 to like 85... See how high you can get it before you get Agro...

Then try to break that record.

Yeah the % game is what I normally do, but sometimes I just root the slow right away. I miss playing a Rogue, life was easy, get behind mob and kill it.

Tash and slow immediately if playing with a paladin/shadowknight (and if you get aggro for longer than a few seconds you know you're playing with a bad one).
Tash, root, slow if playing with a warrior or other non-snap-aggro tank type.
Use the low-level root so you don't consume too much mana doing this. 30 mana is an acceptable insurance policy.

in both cases (at your level), if you can't land a slow early don't bother with it; thus the root prior to the slow. If you are waiting for % health by the time the slow lands it'll be basically useless (again, at your level). So root is your friend if you are not playing with a knight tank.

If the mob is equal or above the level of a warrior tank consider that taunt won't work on the mob, so you can't rely on the tank taunting slow off you. Also consider root will likely break early.

Something I've seen some people do against harder mobs, when a warrior is tanking, is to memblur the mob after it has been slowed. Not sure if this is a good idea, but at least it helps ensure the mob won't be beating on you after slow, even if it screws up the warriors lead!

Lvl 29? I prolly wouldn't bother

this is pretty on target, its nice to want to slow but really if you just root pulls for tanking, C everyone, an occasional mez during bad pulls, you'll be doing fine at this level as a groupable enchanter.

Besides keeping haste and clarity up, would you be casting suffocate each mob?