While playing Path of Exile can be a mostly pleasant and stimulating experience for action role-playing game fans, there are still a few things that casual fans tend to get nervous about. One of them is grinding out the levels, which can be such tedious busywork for the most part, especially if played with a melee character. Some would say that you might as well go with a magic or ranged character with greater propensity for AoE damage, but the true feel of an ARPG can only be felt in the sensation of a melee character's meaty hits on enemies around him.
This is why an optimal way for leveling up with a melee character is needed in order to get the most out of Path of Exile, and there is one. This is not merely a build, but an overall guide on how to level up quickly with a melee character like a Marauder or Tempest. In this case, let's use the Marauder as the basis for this guide. The most important thing to consider is a compatible AoE active skill that can then be built up to do most of the damage.
If you wish to respec it later to create another build, then you may do so. The point here is to take the character level to the maximum so that you can do that without being stuck in a lower level for long. Fire is always a good idea, and Flameblast performs pretty well for this purpose. You can then ramp it up with Flame Totem with Blind, which is actually better than Searing Bond due to both synergy and what it does to enemies, and you can add Faster Casting to go even faster. What you end up with is a great way to turn monsters into burned toast in a matter of moments, which brings in all the experience points very quickly.
There are tons of other ways to get the experience train moving, but it seems that Flameblast is getting a lot of traction quite consistently due to how good it is, which has made it a fan favorite in the game. The basics are Flameblast with Chance to Ignite, Elemental Proliferation, and Concentrated Effect for the most amount of damage to as many enemies in as little time as possible. You can then amp it up with Fire Penetration if you have a 5-link, and then Increased Burning Damage if you have a 6-link.
That fire damage can also be buffed with Flameblast's initial hit and ignite, and you can focus on health and mitigation as well. If you're playing in Softcore league, then you can forego health nodes for more that deals with fire damage and so on, so long as it makes Flameblast better.
If you wish to make use of other active skills, then you may do so just as easily. Just take note that you need an AoE active skill that can be augmented with support gems and your passive skill build. If you're able to tie everything together and make ends meet, you'll find that your character can shred through just about anything very quickly.