Nice deck, i like it.

Why only one violet teacher, otherwise looks fun

Looks interesting but a bit weak in the early game, only 6 minions in the 1-3 mana range

First of all we have to get the combo in hand, so we draw cards and delay our opponent till we have the combo ready in our hand and enough mana to play it. For that we have to consider the health/armor of our opponent as well as our damage spells. There are a number of different combos we can plays. For all of them we have to have the malygos as well as the Kobold illusionist in hand, but no other minions, so that we can be sure, that the Kobolt illusionist puts the 1/1 copy of Malygos on the board and not of the Elven Minstrel.
So (most of the time on turn 10 but with Preparation in hand it can be played earlier) we always play the Kobld Illusionist first, and trigger its deathrattle to get the spelldamage from Malygos. This can be achieved by the Necrium Vial(maybe prep it, to save 3 mana), by attking with the 2nd charge of Necrium Nlade or in some instances Eviscerate on the Kobold illusionist. When the opponent has 30 hp, we need to put at least 2 copys of malygos on the board ideally 3, since this gives us +10/+15 magic damage!
The third step is rather simple: we just smorc face with our buffed spells (Backstab, Sinister Strike, Razor Petal Eviscerate)
It is crucial for the combo to kill the opponent in this one turn, so we have make sure we have enough burnspells and mana to kill the enemy in one turn.
To be able to use the Backstab on opponent it is rather useful not to attack with minions or weapons before we have the combo(If they damage themselfs we cannot change this).
Against slow decks it is quite strong, but very hard to win against any early agression, unless we have perfect draw.
This deck is not super refined yet, since there are may more variants to try, some other cards to consider are Sprint, Vanish, Deathknight, and many minions to consider, although we do not want to delute the minion pool too much, since we want to be able to draw our combo minions with Elven Minstrel.
I hope this helps. And feel free to ask more questions.