Blue Blazes is an ability for Snapdragon in Plants vs. Zombies: Battle for Neighborville. When activated, Snapdragon launches a blue fireball that follows and attacks enemies. Its closest zombie counterpart in-game is the Super Ultra Ball. The projectile deals 125 damage to enemies hit by it, but will also deal 15 splash damage.
You should use this similarly to the Super Guided Ultra Ball. It moves much faster than it, however and it can burn its target unlike it.
If you want the fireball to track enemies, you need to aim at the enemy for the entire duration of the fireball charging up, as with all homing abilities in the game. It can deal a powerful 75 damage, so you can instantly kill weakened enemies and Imps. A powerful strategy is to fire Blue Blazes, sprint away from your previous location and appear behind your targeted zombie, and use Flame Blower. The enemy will be focused on the fireball so they wont see you coming.
This attack is never the most accurate and even though the projectile moves fast, the homing power isn't too strong. Also, if you don't aim at a target, it will not home onto any other targets, so the attack will be useless unless a zombie walks in front of your fireball. This is very unlikely because of it's slow speed and the way it's shot which makes it easy for the fireball to go too far upward or downward.