Well like I said, it's the game of breaking the game. the idea is to combine the individual card rules in such a way as to give yourself the greatest advantage possible.
There are two ways to build a magic deck, from my understanding: High-level, and low-level strategy. High level strategy is in the build of the deck itself. Everything is geared towards a specific type of behaviour or playstyle. For example, a populate deck is about getting lots and lots of monsters, and swarming your opponent. Lots of cheap, weak monsters, and lots of populate spells.
Low-level is a lot less common, partly because it isn't as devastating, and that's to build your deck so that any given hand can be useful. It's a lot simpler, but still can benefit from some messing with the rules. A buff deck is a good example of that one - get some cheap monsters on the field, and use spells to make them better. the White/Blue I have is kind of a
D Ebuff deck, where the focus is on cheap monsters and spells that debilitate, so I can just chip away at health.
It can be complex, but... eh. It's as complex as the cards in your hand, basically.