Supplant Form looks mixed since it has a strong effect, but 6-mana is steep
We've already been shown one instance of Saga mechanics at play on a Creature card through the example of Summon: Shiva
Hopefully you have a means to draw cards by turn 3 or 4
Some cards and strategies, especially those featured in sets like Tarkir: Dragonstorm and Aetherdrift, are designed to excel in multiplayer environments
A combo can be any set of cards which effectively ends the game in your favor, be that a prison like Teferi + Knowledge Pool, infinite damage/mill, or even a very fast combat clock like Skithiryx, the Blight Dragon + Lightning Greaves
The fact that the deck has two commanders also ups the power level quite a bit because you essentially start the game with two extra cards in hand and fill two spots on your curve