Burna Boyz
Burna Boyz are Orks who cannot stop setting things on fire. These lunatics will set light to anything and anyone for the simple joy of watching them "do da burny dance." They can prove utterly lethal to tightly packed or lightly armoured infantry, the roiling blasts of their Burnas flushing their victims out of cover amid the sizzle.
Often they join forces with Mekboyz whom they depend on to supply them with Promethium fuel, and the Burna weapons from which they get their name. These dedicated arsonists take great delight in setting fire to the enemy (and anybody and anything else they can lay their hands on if no enemy is available) and it takes a strong Warboss or the blackmailing powers of the Meks to keep them in line. However, the benefits of these lunatics in any Ork warband just about outweigh the risks of getting anywhere near them. The Burna Boyz can be a powerful asset on the battlefield, whether in a small team or large mobs; their mass incendiary firepower can prove devastating, particularly against enemy infantry, flushing out foes from cover and bringing down bestial creatures. Also, with their weapons turned to the searing hot point of a blowtorch flame, they can wield them to hack and slice up enemy armour and vehicles. They serve a vital secondary role in this regard, cutting up battlefield salvage for later use.
In Game
Burna Boyz are an elites choice, meaning that they compete for a slot with with Tankbustas, Nobz and Kommandos, and so are not in many armies. However, they are still a very good unit, especially in armies revolving around the use of many vehicles. The primary reason for this is because every Burnaboy is armed with a Flamer, which can be used as a melee weapon with AP -2 in melee. Through judicious use of mass tank-shocking, enemy infantry units can be pushed into compacted formations, making them prime targets for being purged with fire. The ability to unleash 30, 40, even 60 strength 4 attacks which automatically hit is frightening: don't be surprised if your opponent just removes the squad and skips saves.
Versatile Burna - Burnas can be used as either a flamer or Power Weapon, which means they can attempt to cut down MEQ units or Monstrous Creatures (although they still suffer from a crippling lack of strength for this task). However, the choice must be made whether to use them as such during overwatch, if attacked first. If you use the d3 auto-hits that means you cannot use them as power weapons. Considering the average model is MEQ, overwatching on d3 is better as the chance of an unsaved wound is the same chance as hitting and wounding at AP -2 in CC (plus 2A extra per boy in CC if overwatching). Per model basis now means that you can elect to fire with half of the squad while the other half preps power weapons.
Dedicated Transport - Burnas can now take trukks as a dedicated transport. Remember that when you fire from a Trukk, you can simply find one good placement for the flamer and have every single Boy shoot with exactly the same angle resulting in dozens of hits on a same unit.
On the flip-side
They're providing anti-infantry in an army that already has excellent anti-infantry, and they cannot fire from transports if you move the vehicle any great distance. They were much better offensively last Edition, but alongside the Power and Template Weapons nerf came a serous defensive buff, in the form of D3 Overwatch hits per Burna, even if they're in a Trukk. And, since assaulting is an uncertain prospect nowadays, you might get a proper round of firing into the advancing enemy unit.
Furthermore, although Burna squads can murder any kind of infantry when they get close, they are not a fast unit. this means that as soon as their transport is destroyed, the enemy can simply retreat slightly and continue firing at the expensive Burna Boy unit that only has Toughness 4 and a 6+ armour save to protect them. Burna Boyz die just like a 6 point model but pay three times as much solely for significantly enhanced close range damage output, meaning they are entirely reliant on transportation and thus mobility to ensure they come anywhere close to proving their worth in an Ork force. With the big nerf to Ork Trukks through the tweaked Ramshackle rule and an arguable nerf to Battlewagons with template weapons having a greater effect against open-topped vehicles as well as the actual points increase of the unit itself - mandatory assault grenades, hooray for Initiative 2! This means that Burnas are generally a tricky unit to use effectively, although cheap 5-man squads with a Trukk in MSU lists can be very effective infantry hunters, backfield objective clearers and even distractions through their insane damage output against Xenos infantry.