1. What's better to Cut from deck Defend or Strike?
I usually remove a mix of each.
2.Should I chase Synergy or just all around Decent Cards?
Synergy, the majority of the time. If you don't see a card that fits your deck, don't hesitate to skip the reward entirely. In fact, you should probably skip more cards than you take. But don't take this advice to the extreme! It is useful for a deck to be able to do more than one thing, if it doesn't bog you down too much. Think about that if you see a rare card. Or maybe you want a copy of Cleave or something, to help deal with certain encounters.
3. Should I be playing more Offensively and Kill fast or Turtle up and Minimize Damage at all times?
You'll definitely want to have a good idea of how to destroy the enemy, and you don't want it to take forever. If you spend more turns in each battle, you're giving the enemy more actions. In some cases, that's really bad.
But, again, it depends on the circumstance. If you happen to get an early Barricade or something, it actually might be worth investing heavily in block. Do what makes sense at the time, and improvise. Do not start a run expecting to build something very specific.
4.Biggest Noob Traps to Avoid
Don't take too many cards. The more you have, the longer it takes to cycle through your whole deck, which means you'll see your best cards less frequently and you'll be more likely to get bad hands.
Improvisation is better than planning. You are trying to come up with a strategy on the fly, not assemble one that you decided on at the start.
Don't be too enamored by the biggest, flashiest cards in the game. Yes, powerful cards are powerful, and you should take them and make good use of them. No, the game is not all about Demon Form or Catalyst.
5,. General tips for each character and How they should be played different.
Ironclad has a lot of attack options. Multi-hit attacks are great when you can boost your strength. Cards that do high damage but inflict yourself with a status card are highly recommended if you get Fire Breathing and/or Evolve. Headbutt lets you retrieve a card from your discard pile; there are many uses for that. Pommel Strike lets you draw more cards as you attack. You get the idea. Look at what the game offers you early, and pick some attacks that you think will fit.
You start with Bash. Upgrading that will make the enemy vulnerable for 3 turns instead of 2, which makes it a much better card. You don't always need to do that, but keep in mind that it's an option.
Also, Corruption is a very powerful card. Be aware of that, and don't sleep on it.
Silent has shivs, poison, etc. I assume you've noticed some cool stuff you can do with poison. Most people do. And it's not wrong. But don't get tunnel vision. There's a lot of other cards you should be paying attention to. Well-Laid Plans is always nice to have around. Alchemize is fun. And I've had a lot of success with mixed decks as Silent.
Defect is tricky to play, and there are a lot of ways to go about it. I like to take a lot of Loops and orb channeling in general, and if Biased Cognition shows up, I want a copy of that. It bursts down most encounters without too much trouble.
6. any tips for going against bosses?
First, notice that you can see what boss you'll face at the end of the act. It's on the map. So if Time Eater is coming up, you'll know.
Make sure you have good damage output before you get there. I don't care how, but you need a way. You'd better not still be playing 6-10 damage on a good turn.
Remember that you get a full heal afterward.
Other advice:
Fight minibosses. They drop relics, and you get rare cards more often. It's worth the effort.
Use your potions when it makes your life a lot easier. Don't save them for a nebulous "better time" unless you know when that time is going to be (like if a boss is coming up and you're holding a strength potion or something).
Relics are part of your build. There are some that you don't need to think about much, but if you get something interesting like Mummified Hand, take it into account!
Some relics can only be found in shops, so pay attention to the inventory there. One of them is Prismatic Shard, which lets you find cards belonging to other characters, and enables crazy decks that you'll never see again. Another fun one is Chemical X, which gives X+2 to every card that costs X energy. This enables you to play those cards for 0 and still get a strong effect, when normally nothing would happen.
Shops also sell colorless cards. The notorious one is Apotheosis, which upgrades your whole deck until end of combat. There's a lot of general utility stuff like that in the shop, so pay attention to it.