I know how many (or most) people can struggle one an average boss sometime in their storyline. so I decided to create this guide on my favorite strategies.
1: Train School Shield spells from Sabrina GreenStar! Using a shield that matches the boss's school is far more powerful than a Tower Shield (keep one or two of them in your deck, though, and use them againt Balance bosses), and can prevent the minion "stealing" the shield if it's a different school. Sabrina is located in the Commons Fairegrounds.
2: Get rid of the minions quickly. They can have more of an influence than you know in a duel, so they're best gone. Use an Aoe to destroy them. Alongside less trouble, it also weakens the boss a bit, helping the final blow.
3: When battling a boss that is the same school as you, pack Prime Treasure Cards in your sideboard. It's far more convenient than waiting for them to show up in your deck, wasting less time.
4: Keep Wand Attacks! A Weakness is actually a powerful game-changer, and Efreet's negative charm is HORRIBLE to have on you. Wand Attacks can get rid of them. (But don't use one of your own School, or all your Blades and Traps will go with it) In a pinch, Cleanse Charm and 1-pip spells also work.
5: Get a good Pet! Pets with stat boosts, good Item Cards, and healing maycasts are a Wizard's best friend. Look in the Hatchmaking Kiosk for one that suits your tastes.
6: If the going gets tough, don't hesitate to call on others for help! Use Team Up or ask a friend to help you if necessary.
7: If you're fighting a cheating boss, there are often helpful guides provided by the community. Alter your strategy appropriately and try to have someone else help you!
8: Try doing Side Quests for Experience and grinding enemies for better gear. It really helps.
9: If, after all this, you still can't do it, take a break and try again later.
The biggest pieces of advice I can give people are these:
1) If you need a hit all spell of your school, and dont have one, buy the TC version until you can train yours 2) Once you have your hit all spell, buy the sun school enchantment tcs until you can train them. 3) always, always, ALWAYS use blades over traps (unless a blade triggers a cheat you can't deal with). Blades affect the spell over ALL monsters where traps only affect ONE monster.
4) if possible, have a pet trained early in the game that gives you whatever your desired talents and item cards are. 5) use the best gear you can manage at all times. 6) less is more - if you can, use LESS cards in your deck, instead of more. This works a lot better with reshuffle trained (and helped more with a balance mastery amulet). 7) Sometimes, a one hit kill is better than killing off the minion separately. IF you can take the punishment from the monster hits, while blading up, and using the sun school enchantments where possible, one hit spell could kill both monsters. It's a balancing act, find what works best for you.
Lookit's 2nd post has sound advice for ANY level. To find out why a boss might be kicking your butt, google it. Google is your friend, BIG TIME! I've been playing for about 6 years I believe, and Wizard101 Central has been my go to for answers most of the time. Other sites like Duelist101 work for me as well, but I prefer the layout of W101 Central. That said, use whatever works for you :)