At the very beginning in Unicorn Way, you get a wand that gives you a six-pack of cards from schools. Look at the health of the monster, then try to pick the card with the most accuracy that will kill it. That is usually Imp. There is no point to picking the Storm Snake to kill it if the Life Imp will do the job, since it is more "accurate", its likelihood of success is more, 90% vs I think 70%.
At some point you will get Pixie to heal. Put two in your deck.
At some point you will get to Level 5. Find the Bazaar and buy a wand, but something other than your school (of Death). Balance isn't bad, you are the least likely to hit another school's trap with that one. Wands do low damage, but cost zero pips to cast and are 100% accurate. They are a sure thing, great if something has like 44 or less health on them. Or if you got to say a wand that is 50, you know that a monster with 150 health will be taken down with three hits, unless the wand matches the monster's school, or, the monster shielded against it. Not many monsters shield against Balance, the only shield against it is Tower Shield. You will have a problem against Balance monsters though, just use your regular death spells.
Without a blade or trap, in all schools except Death, all spells do about the same amount of damage per pip when compared to the other spells in the same school. So Storm does more, but when you divide the hit by the pips, its about the same number for most Storm spell. Death is different, because Death gets health back for many of its spells, usually the even pip ones. Because of this, you must learn to use Death Blade. You will also want to pick up using Death Trap.
Around this same time you will want to take the rank one dark sprite spell out of your deck. You will use your wand for small hits, and the higher rank spells for big hits. This is true for most schools.
At level 10 you start getting power pips, those yellow dots at your feet in a battle. Actually you can get them earlier if you buy the right ring or athame at the Bazaar, it will have a symbol that looks sort of like a small sun on it. At that point you need to start trying to stay more to your school. Further on in the game, you will find that you will want to stay with spells that have an even number of pips if possible, to be "pip efficient".
Once you get the hang of it, you basically want to try to kill the boss with a massive hit that gives you health back and you are ready for the next battle. There will be a period of time when Ghoul just doesn't seem to cut it, and Banshee doesn't give you health back. This will be the difficult period. Learn to use that Pixie to heal and sweat it out. Later on, maybe in Marleybone, you will remove Pixie from your deck, when you get good at getting health back.
At some point you will get fight a death monster solo, that is, friends can't help. This is to teach you the value of prisms. Learn it. All schools except Balance need to learn it. You can go to the Bazaar and buy a few Treasure card versions of Death Prism. But practice using Treasure Cards in Unicorn Way first (not the costly prisms) until you get the hang of it. Applies to all schools.
At some point you will get the spell Sacrifice, takes 250 health from you, and gives 700 to anyone in the battle, including you. You may want to cast Death Shield before it, so put a few of those in your deck too. You also do NOT want Death Blade on when you cast this spell. You will have to hit something, then try to heal.
You may want to train up to Life to get Sprite., which does almost the same amount of healing as Pixie for one (white) pip, but its spread out over time.
With this you know have four ways to get health - health steal spells, Pixie, Sacrifice, and Sprite if you trained it. If you manage to get a pet with Spritely, now its five ways. In fact, you will get so good at it, you might want to consider going first in a battle, to fully take advantage of your health steal. You take the hits, your health goes down, and then you hit and get it back, while the team members concentrate on hitting. Just watch out for Life monsters, they put up Death shield, let some one else volunteer for those.
No matter what school you are in, usually you defeat the monster with the least health first. As I say to my kids, dead monsters don't cast spells. After you defeat the minion you cut about in half the amount of damage you take, and you can focus on getting "the boss".
Almost all schools at some point purchase a wand opposite of their school, except Death and Balance. The reason for this is when faced fighting a monster of the same school. Say the monster is Storm. Storm monsters throw up Myth Shields, their opposite. Now if the Storm just casts a Storm spell at the monster, it will get reduced. So the Storm puts a prism on him to convert to Myth. Ha, but there is a Myth Shield up. The problem went from bad to worse! If the Storm had Storm Blade on, that blade will trigger, go into the prism, convert to myth, get to the prism, get reduced, and end in a small hit. Arrgh! Solution, cast a Myth wand hit to remove the Shield. Order is important too! If the prism goes on and then the monster casts the shield, its fine, but if its before, at some point you will want a spell flying in there to pop the shield.
Now Balance doesn't have an opposite, so no need for them to get an opposite wand. Death monsters rarely, if ever, cast Life Shields, so you are better off with the Balance wand just so you don't pop other schools traps. Balance monsters will put up combo Life/Death/Myth shields on you. Either Switch to a death wand (but then you pop your blades!), use a damage over time like Poison (better), come up with a massive hit and realize it will get cut in a half (just ok), or try to do a small hit, then a big hit (time consuming).
Or if say your friend is Storm, carry a Myth wand, you can pop the shields off for them. Myth school comes well equipped dealing with Myth Shields, so there is no real need to help them against Storm monsters, but Myth against Myth, they might need a Storm hit to remove the storm shield for them.
But for general use, in places where anybody can join you, in my opinion, a Balance Wand is best for Death. For Life, a Death wand is best, but they need to make sure they don't wand a Death Trap off.
I pay attention to the kinds of mobs I will be fighting. For instance, if a mob or two are Life, I will load up on poisons. My wand is always another school (so I can get rid of the -25% spells) I keep my deck short. So, usually I have the following:
7 Death Blades 7 Death Traps 7 Feints (boss fights only) 7 Wraith or Scarecrows 7 Death Prism (if fighting Death mobs) 7 Poisons (only if Life mobs)
Sometimes I do equip a Death Wand (sword) of some sort, to get rid of pesky Death Shields).
That's it. For fun, I started soloing Malistaires lair and with that kind of deck layout, I was able to drop the first two bosses (Gotuks?).
Normally, laying a Death Trap, and having a Death Blade on, you can hit for around 1400 Wraith damage to a non-Life mob (Death does boosted damage to a Life mob).
Though, more and more, I keep my Death Prisms in my deck, so if some mob pops a Death Shield, I slap a Death Prism on him. Note: always cast Death Prism BEFORE Death Trap.