If you don't understand my title, Marduk (Human) means the human form of Marduk.
If you are now saying anything remotely close to Whaaaat? you should take a little time and get a little further in the storyline of Aurum Blade. But crap, I already gave it away.
The first form of Marduk is very easy. The second one, not so much. In fact, I haven't beaten the second form yet. But like I said, the first form is easy.
1) How do you get there?
A bit of a noob's question, but I'll answer it with a noob's answer. It's on the 25th floor. In one of the rooms (yeah, it's confusing) there's a jump circle in the center of the room. Ding!
2) What should I bring?
The same old. Potions, good gear, and (a) good Blade(s).
3) How much health does Marduk have (ha, accidentally spelled it Marduck first)?
A health bar fit for a boss. But here's a hint: it's less than Sirens. Either that, or beating Marduk was less complicated.
4) Any special tricks that can be used against Marduk?
Stay away from him and let the Blades do the work. Use ranged attacks. Oh, and get a Step 10 Stone Blade. Then, there's three of your little friends.
5) What attacks does he have?
From the start, he has this blue ball of energy. I'm not sure how much damage it typically deals, but it's 1100-1200 on my Step 9 Stone Blades. That's why you should stay away.
Then, he acquires a second attack. See if you can recall Wooden Destroyer, the first boss (that tree dude). Marduk's attack in common with him is the spikes that thrust out of the ground. However, these deal less damage, about 400 to my Blades.
Just because you beat the first form of Marduk doesn't guarantee you'll beat the second.
PS: Xusha is alive and well. Stupid rumor.