HOW TO DO THE QUEST:
1. Go to the firs quest 'Basalan Town' and do the 'Report of dark matter collection'. The summoner will tell you about the details of this quest.
2. There are two Dark Collection in 'Dark Forest' and the other two in 'Spirits Sands'.
HOW TO DEFEAT DARK MASKO:
To defeat easily Dark Masko, just use any Dark guard (preferably MAGIMAN) and build him up with High-Magic-Defense and High-Magic-Attack. For your own option, Speed also is a good to keep up, this is for you to be safe in double-attack advantage.
HOW TO DEFEAT THE DARK SUMMONER:
Preferably you should be above level-20 to have a easy fight with this guy, but it will takes a lot of luck if you want to beat him in low level 20. Just make sure you have a good built with your Guard , specially with MAGIC-ATTACK, MAGIC-DEFENSE and SPEED.
These are the good GUARDS to fight AGAINST his GUARDS:
LVL 20 Dark Summoner
1. FIRE TRIFISH against BIGIWORM
2. BULBHEAD against MAGIMAN
3. MAGIMAN against DARK MASKO
LVL 30 Dark Summoner
EOSTRE/BULBHEAD + GREEN MAGIMAN + ROROCA(magic-attack type)