9th Dawn III

For this achievement you need to morph a creature 50 times. In order to morph a creature it needs to be level 90-100, and you need a morph stone. You can buy them in the shops that sell monster bait and traps. When you use a morph stone, the creature loses a portion of its stats, delevels to one, but gains a tiny of combat rating (which dictates stat growth I think). How much combat rating they get appears to depend on the morph stone you use, and your creature rearing skill. Anyway, basically they need to level up 4500 times at least to morph them 50 times, which means this achievement is basically just a level grind.

As for leveling, you only want one creature in your party as experience is shared, so having a party of ten means everyone levels up much slower. As for experience boosts, you can either make an experience potion via Alchemy, or use the yellow bloodspawns (checkpoints) you see. There's one just north of Castle Lorwick (sp?). The boosts don't appear to stack and I have no clue which is better, since no numbers for experience are shown anywhere that I can see.

As far as where to go, if you intend to master every recipe for the achievements (weapon smith, armor smith, weaving, alchemy, jewel smith) you will morph a creature 50 times WAY before you master everything, so my advice is to take a creature along with you while you're farming and morph it as you go. To give you an idea, I have 500 Molten Dragon Cores from farming, and I need about 2500 for mastering recipes. You don't need any extra effort at all. If you aren't going master everything, running through the Gauntlet or Scorn of Hell is probably going to be the fastest you can be.

NOTE : There is an achievement for getting a creature to level 100, so make sure to hit 100 at least once while you're grinding this out.