I wish there was another Main Phase, so combos could work a lot better. For Example I attack with a creature and then sac it to my Rothus, the Traveler coming into play on the second main phase, so that creature is not wasted.
Plus there should be molligans, since most of the time my hands consist of high costing cards with a deck that has more than half 3 or less costing cards.

P.S. in the future i wish some of these rules get changed for even more strategy.

Mulligans wouldn't help when you only have 5 cards to start with. A Main phase 2 would be useful, but Wizards wants this game to be as streamlined as possible. A second Main Phase is unneccesary and potenially confusing to new players.

Plus, only one main phase means you really need to think ahead with what you do.

Part of the point, though, is to be different from Magic. Yes, there are a lot of similarities in the basic gameplay of the two, but adding a second main phase would simply make the games too similar.

A single casting phase just means that more planning is involved for your turns, and you have to plan further in advance.

As far as mulligans go, I agree with the earlier comment that they're a bit on the pointless side when you only start with 5 cards. Not to mention that it's almost impossible to really get mana screwed in this game - that's why it's designed the way it is. If you're regularly drawing hands with such high cost cards that you would need to consider mulligans that often, then either there's something a little off with the deck design, or you've just got *really* bad luck. :)

Later,
Cal