Guide: The Beast Within by Azulmagia

So you're ready to take on the latest Assault mission, eh? Well, you best be, because the target's you! The Beast Within is notoriously infamous. It can be best summed by the phrase "somebody dies, and fast". Who will, exactly, depends 50% on how you prepare for the fight, and 50% on luck. Good luck.

Obtaining a Testimony
BLU, COR, and PUP by far have the most difficult testimonies to obtain. Only a single monster will drop your test: Mamool Ja Mimickers. There are two areas to choose from: Wajaom Woodlands and Mamook. There are pros and cons to both.

Wajaom Mimickers are lower level, which means less people are needed for help. Additionally, the repop time is only five minutes, allowing ample healing time without having to wait very long for a repop. Unfortunately, there are only four total spawns throughout the entire zone, and they're all spread apart meaning you'll have to make do with a single mob (by the time you heal and reach a different camp, the one you just killed will have repopped by then). The most effective camp for me was the Aydeewa Subterrane zone at (H-10). There is a lone Mamool Ja Mimicker along with a Woodland Runner here. The good thing is that the raptor generally keeps away from going too far west — you should have ample pulling space using a ranged weapon. Fights here can be safely duo'd at 70.

''Note: It is actually possible for a BLU70/THF35 to solo these using Zephyr Mantle and Diamondhide, however, it is extremely difficult due to Firespit (inflicts 300-500 damage). Firespit is absorbable by three shadows, and the mobs will always check Tough to a level 70 character. Do not silence them, but take care not to get silenced yourself — breath spells wipe shadows, so take care to stun them.''

Mamook Mimickers are relatively abundant, providing you with an ample series of fights before having to wait for repops. On the other hand, they're a couple levels higher than the ones in Wajaom, meaning you'll need more help for these fights. Other Mamools roam closeby, so there's a high probability of getting links. Additionally, Mamook is a beastmen stronghold — which equates to 12 minute repop timers. This camp is recommended for larger groups only. Mimickers can be found throughout the central (and surrounding) areas of the first map. The easiest way to get there is by taking the Mamool Ja Staging Point.

Farming a testimony could potentially take hours. I have gone 1/1 and 1/47. At the time of writing this guide, the drop rate is recorded to be about 5% for both areas. Check the Mamool Ja Mimicker page for the latest drop rate records. (You could also do your fellow Blue Mages a favour by update the rates with your farming records.)