After reaching level 130 and finishing all of the worlds in Ascension 2, you can ascend into Inferno Mode. Inferno modes start at tier 0, going up to a current maximum of tier 5000.
The level of the Creatures are constant over each world in an Inferno Tier. Each subsequent tier adds 150 to the level of each monster, and each world after the first world adds another 15 levels.
Monster Level = 100 + 150*(Inferno Tier) + 15*(Planet Number-1)
Each Inferno Tier adds 1 to the possible number of Cards that can drop, shown by the following formula:
1 + (Random from 0 to Inferno Tier Level)
Each Inferno Tier increases enemy's HP by 1% and furthermore per 10 Inferno Tiers enemy's HP is increased by 2%, per 25 Inferno Tiers enemy's HP is increased by additional 5%, and per 100 Inferno Tiers enemy's HP is increased by additional 10%. E.g. with Inferno Tier 21 enemy's HP is boosted by 25%, with Inferno Tier 100 enemy's HP is boosted by 150%. Creatures' HP values are shown here.