Hi @gargi, thanks for curiosity..
First, you have to understand the battle rule set, and Mana after that you have to choose your summoners.
Battle rulesets clear that which summoners/Monsters will be effective for the game play.
Suppose that you got Up close &personal ruleset where we can use Melee Monsters. Then you need to choose your Melee attack additional summoner and Snare ability Monsters along with Demoralize base Monsters.
One more thing that you have to notice is opportunity, sneak ability Monsters as all Melee Monster do not attack from any position..
If you keep these are the things in your mind then game will be interesting for you.