This new rental system has made this game amazing. Here is where you can rent.
So everyone that is new to the game and rentals learn the game real quick and then you can rent some cheap monsters/summoners to help rank your self up. The goal is to rent 1 splinter type for as long as you need. Then rent your daily splinter each day or your next favorite splinter, so you have 2 decent splinters always.
This picture explains the highest monsters and summoners you will want to rent. So if your highest rank you want to get is bronze you can buy/rent a legendary summoner or a level 3 common summoner and get monsters that work with that summoner. So if you go Malric inferno for fire make sure you rent a level 3+ summoner and monsters that are melee that have sneak so they can attack from anywhere. If your missing power just rent a gold card to make your your next rank.
When you are in bronze you can make around 2-5 dec a win. Then when your silver 6-18 dec per win. Then gold you can make 18-50 dec per win. Then daily quest you can get 1 per day from bronze then 2 from silver 3, 3 from silver 2, and 4 from silver 1. Then 6 from gold 3, 7 from gold 2 and 9 from gold 1. So the scaling from ranking up real makes a big difference on what your profiting.
The daily chest loot chance is 33% dec, 33% potion, 33% card, and 1% a pack. The dec prices and card prices have been jumping up the past few months. So you can buy some cards and hold on to them and use them or rent them out. This game has been doing amazing. Just today $122,911 worth of cards sold. Then the daily rentals is $1,884 a day. You can rent some of the best cards in the game for only pennys a day. Here is some of the most expensive level one summoners prices per day
If there is more people want to see or learn let me know.
Thanks and good luck hunting.