Just yesterday I went into the Waterworks with two good friends. One had to leave in the middle, so my other friend and I decided to finish the tower. It was hard, but definitely doable, even for a team of two fire wizards. Yes, we both had life as secondary school, and I had the life mastery amulet. But those are not the characteristics that enabled us to succeed. Our success was due to teamwork, mutual support, and the ability to think ahead. We could have been defeated on two or three floors, but our combined skills and many months of experience with battling together all made a recipe for success. And I got my Firestarter boots! WOOT :)
I have one crazy friend who likes to solo the Waterworks. It's doable, too!
My friend and I have been abandoned before for various reasons and have always come out on top. I mostly use my death and her an ice wizard.
Death takes the first spot when fighting luska because death gets a boost on the balance boss and can use boosted bone dragons and wraiths for big damage while ice spams frost giants and snow angels.
The fight with Sylvester is a similar story. Ice spams it's big area attacks whittling down death and fire health as ice gets a boost against both bosses. Death pips up in trap rounds and then attacks with wraiths and dragons with blades again, first focusing on the fire boss. He should drop quickly. Ice's relentless attacks will drop the death boss shortly after. Once fire is down, death switches targets to Sylvester and dragons and wraiths as they need the health. With two people though, it would be wise to equip the amulet with reshuffle.
Since death isn't carrying traps, this leaves rooms for any combination of death shields, dark pact, sacrifice, plague, and virulent plague. This way I can heal as I need because with her attacking everyone all the time, she'll be the focus of all of their attacks and 41% resist all can only go so far. I also like to carry a lot of treant poly morphs in my side deck. One poly morph can and will turn the tide of battle back to your side.
This is without using more advanced tactics such as death dispels to change the bubble, storm dispels to keep your blades into a trap round and myth dispels to keep traps into a blade round. Fire dispels are also good because he likes to waste his power pips on meteor. A life dispel towards the end of the fight is good too because I've seen him use a weak satyr on himself once he's below 5,000hp. An infection might be a good idea too just to make him further suffer from his own doom and gloom.
The biggest thing to remember is that once you get Sylvester by himself, he is no real threat. All the damage comes from his minions just like every other boss fight.
The hardest part about the dungeon is finding a group of people that will go the distance and know what they are doing. Go into a crowded realm and everyone wants to go in only to back out at the last second. Go into a normal or perfect realm and you'll find people waiting for their friends to show up.
I completed the waterworks in 2 hours with just a death and balance. People really overrate the dungeon, its time consuming, not hard.
I agree on time-consuming. My Balance wiz once went in with a Life and another Balance, and it took us well over 4 hours... That said, both are defensive schools and don't have a ton of high-powered attacks, even with buffs (when we're allowed to use them) and crits. But we managed to figure out a strategy, stick to it, and complete the instance without getting killed.
Another time, I went in with three Life/Death wizards, and the fight was very short. It doesn't matter what school the people you bring with you are- whether or not they know what they're doing is what really makes the difference.
And I confess- my first time in Waterworks, I wand-ed on a boss, because I wasn't aware that we couldn't. However, as soon as I discovered the unpleasant things that would happen if I did (getting spammed with feints and bone dragons), I learned quickly not to do it again. :P If you have a teammate who has done it before and can explain the strategy to you BEFORE you make my mistake, then so much the better. :)