This is one I have seen many players as questions on. Once you understand how to look up this information to what max level your summoner will summon during a match it is quite easy.
During matches, the game will use your highest summoner you own of the one you selected.
The best way to understand is just with examples.
Example 1:
All you have to do is go to your collection, click on your summoner, take note what level it is and then click on stats and look at the table.
On the stats page, we can see the chart with all the different rarities and what level that can be summoned. I have outlined it in red to make it more visible.
In this example, he would summon a level 1 common (grey), a level 1 rare (blue), a level 1 epic (purple), and a level 1 legendary (gold).
Example 2:
My Alric Stormbringer is level 3 and we can see from the table he will summon level 4 common (grey), level 3 rare (blue), level 2 epic (purple), and level 2 legendary (gold).
Example 3:
If you think all the summoner have the same exact table you would be wrong! The cards rarity also affects things. As we can see from this epic Talia Firestorm summoner his table is different. With him being epic his max level is 6 and we can see he can summon a level 10 common at that level! He also costs a lot more per card to buy and does not provide a bonus.
Example 4:
My level 6 Malric Inferno can summon a level 5 epic monster. What other monster levels would he summon for common, rare, and legendary?
What If You Over leveled A Monster?
If the card is to high level that is ok it will just be summoned in at a lower level during the match. The game will let you know by putting these yellow triangles on cards that are affected and show you what level they will be used at when you at the prepare for battle screen. Which is nice to see how their stats and what abilities if any they will have.
What Summoner should you use?
That is all up to personal preference. Not something I can answer for you.
XP?
If you do not know how many cards it takes to level up this is the chart many players use. I did not create it myself and it is acquired from the Steem Monster discord link provided below the chart.
https ://cdn.discordapp.com/attachments/486206423815028747/502509194583212046/Card_Level_SM.png
As far as what levels to go for that is more into the theory crafting side of this game and will be covered in a later post from my own point of view on it.
Steem Monsters Fundamentals:
Information
Screenshots were taken and content written by @enjar. Screenshots are from a game called Steem Monsters. Affiliate link