Record of Agarest War

Once you gain access to the Boundary Plane, you will have to fight your way through several bosses to unlock further areas. After defeating all of them and every red node on the initial plane, the Holy Dragon Battle will open up on the southernmost tip of the area. He will be alone the first time you defeat him and the standard boss tactics discussed in the Roadmap and for The Fifth achievement will stand you in good stead. If you are playing on Hard, you will still unlock this achievement the first time you defeat the Holy Dragon, however, you will have to defeat him again (this time with additional enemies) to unlock the extended Boundary Plane. Save before facing him and reload until you arre fighting one dragon and one or two Nils for the easiest fight.

It is after this point that levels start coming thick and fast in groups of 5-20 for a single Hard mode boss battle. When allocating stats, increase STR and INT to 999 first and then switch to LUK. This will increase the drop rate for items which is going to be a big help when it comes to gathering crafting materials. The one exception to this is that you want a character with high Agility, going before bosses if possible. Leonhart is a prime candidate for this as he should be at the center of your formation, no matter who else you are using, because of his Energy skill. Even before he caps out at 999 STR, begin to build his AGI stat so the he at least goes first in random battles (getting off a few casts of Judgement before they attacks makes them much more manageable) if not boss battles. Stop once he reaches 500 AGI as with his eventual 50+ AP (100+ max), combined with AGI that high, he will go before any boss save perhaps Chaos.