Vallari is a mage hero that is fire based, so she works much like Avril except she does more damage at the cost of no crowd control, I prefer using Avril and find there are better heroes to buy than Vallari.

Flamestrike (costs 1 mana)
Vallari summons a Flamestrike at the target area, a short time later igniting it into a burning inferno for 3 seconds that deals X burning damage per second to enemy units inside the inferno. Units that die from burning damage will explode.
This ability is much like Avril’s blizzard except it deals more damage but doesn’t freeze enemies

Lotus Fire
Vallari’s normal attack has a 25% chance of releasing an explosive fire orb, dealing X burning damage to the target and a smaller amount of burning damage to nearby enemies. Units that die from burning damage will explode.
This skill deals more damage than one would think. Worth putting points into.

Crackling Flames
Through countless hours of research and training with fire magic, Vallari can split her normal fire attacks into X seperate flares.
This skill adds considerable damage to Vallari worth putting a point into.

Rain of Fire (costs 3 mana)
Vallari summons 3 fireballs to strike the target area, each fireball dealing X burning damage to enemies struck. Units that die from burning damage will explore.
Not worth the time you have better spells to cast on other heroes.

Burning
Vallari’s fire attacks cause a burning effect that deals X burning damage per second for 10 seconds. Units that die from burning damage will explode.
This Is probably the best skill out of all of them because of how long it lasts, it is very likely that the units will explode because your army will be also damaging them.

Fire Dance
Vallari activates Fire Spirit, greatly increasing her movement and casting speed for X seconds
Not really worth the cooldown unless you have no other spells left to cast.

Building Vallari
(Never bought her so I don’t have any data)

Equipping Vallari
Equip her as you would Avril.