Guild Wars 2

I’m currently running a level 11 Elementalist (S/D) and I have learned to stack 6 might with the ring of fire and Fire 2 and 3. What other skills grant might; and do I need some traits to gain might on switching attunement?

any blast finisher used inside a fire field will apply might to nearby allies

http://wiki.guildwars2.com/wiki/Fire_field
http://wiki.guildwars2.com/wiki/Blast_finisher

additionally, lava axe grants might on skill 1, fire aura grants might when you get hit, and the heal glyph grants might when used in fire

and there are traits that grant might, yes
the one that gives might on attunement swap requires 10 points in the Arcana trait line

there are also equipment upgrades that grant might
http://wiki.guildwars2.com/wiki/Might
seems to be missing the bit about lava axe as that was a relatively recent change, but it has most other things

http://wiki.guildwars2.com/wiki/Pyromancer%27s_Puissance

High level trait.

rhodoc.2381:

http://wiki.guildwars2.com/wiki/Pyromancer%27s_Puissance

High level trait.

Nobody uses that – it’s inferior to Persisting Flames, the alternate fire Grandmaster trait.

The best way to stack might is with S/D, then LH AA in fire fields (given by Embers, a second Ele, a guard’s 2 fire field utilities, a war’s longbow, etc).

Fire Atune > Dragon’s Tooth > Ring of Fire > Phoenix + Arcane Wave > Earth Atune > Earthquake > [Churning Earth if prestacking; skip this step if stacking on boss] > Summon LH + Water Atune > LH AA [assume fire fields from outside source].

You’ll pull off 5 blast finishers within your own Ring of Fire (either with Churning Earth or with a single complete LH AA chain before RoF expires) giving the party 15 might, then you’ll do a blast finisher every 3rd attack in the LH AA chain, giving 3 more might to everyone as long as there is a fire field in place (Embers ftw!). It’s possible to stack up even more might if your other party members use their own blast finishers within your fire field (banner summons and 5 attacks, Cluster Bomb spams, etc) or use utilities (eg. FGJ spams + Sig of Insp activation, etc).

Sigil of Battle is also commonly used, as it grants you might on attunment swap (which you’ll be doing a lot).

In earth attunement, earthquake and churning earth also count as blast finishers.

So a simple sequence could be: Fire #2 > Fire #4 > Fire #3 > Earth#4 > Earth#5.
12 stacks of might right there.
If you have the utility skill Arcane Wave unlocked, you can also cast it instantly for 3 more, up to 15.

Sigil of Battle will give you 3 stacks on attunement switch (every 9 seconds minimum, but you can easily maintain 6 stacks with it), your healing glyph skill grants 3 more if used in fire, and for 10 points in fire magic traits, you can pick a trait that gives further 3 for each cantrip utility skill you use (lightning flash, cleansing fire, armor of earth, mist form).