3k in a single spell...?
I dont see how that's possible.
Spell crits are normally 50% extra damage, unlike melee crits which are 100% extra damage.

Certain trees have talents that allow you to boost it beyond 50% (e.g. Frost tree for mages and Destruction tree for warlocks) but Fire tree doesn't have that option.  Instead we can boost crit damage with Ignite (40% DoT).

Pyroblast does about 800 dmg.

With an Arcane Power build, a crit might be:

800 * 1.5 (crit) * 1.35 (Arcane Power) * 1.4 (dot from ignite) = 2268

With a Firepower build, a crit might be:

800 * 1.5 (crit) * 1.1 (Firepower) * 1.4 (dot from ignite) = 1848

The calculation of the thoerical max damage that can be done by spells.

So, lets use 890 as the highest damage.

890 * 1.10 = 979, So a fire mage can do 979 damage max on base hit.

Now for the critical and the other spell Curse of Elements.  Based on some tests, Curse of elements can increase the damage of fire by half the amount of fire resistance pushed into the negative in percentage.  The highest curse of elements I know is 75.  So 37.5% damage increase to pyroblast.

979 *1.375 = 1346(approx)
1346 * 1.50(critical damage) = 2019

Now for ignite boost of 40%

2019 * 1.40 = 2836(truncated)

And for the final 268 DoT

2836 + 268 = 3094(truncated)

So a theorical max of 3094 is possible.  Now all we need is the best suit for a full fire mage.  That could increase the damage overall to 3500 or higher.

You guys seem to underestimate rogues. With the introduction of the new pvp trinket most players can counter your polymorph affect.

Yes it can only be done once, but if the player waits till u begin casting u will get owned. pyroplast is only good vs inexperienced players or if you get the jump on your opponent.

Also you guys are obviously very inexperienced, outside of duels, pvp is random, it wont occur when ur combustion spell is always cooled down trust me, and you wont always get the jump, as a mage u should hardly ever get the jump.

I have a 57 combat rogue with improved ambush + prep. a crit on an ambush (25% normal + 45% talent = 70% Chance) will kill (or at least take u down to 1/3-1/2 Hp) cloth wearers, warlocks being the exception if they have a soul link with their pet.

As a mage you shouldnt rely on Crits, thats what a rogue does.

I accept that Mages can do more damage than a Rogue and can bring more to a party.

Whats better at PvP? Rogues or Mages?

You decide.