There’s a noticeable change in difficulty at level 61+ and at 70. Once you’ve completed the Campaign Mode (killed the end boss of Act V) you have access to Adventure Mode which unlocks access to Rifts and Bounties and, once you’re level 70, higher Torment difficulties and Greater Rifts, where I guarantee you’ll be able to find a challenge. The health of mobs in GRs goes up 17% every GR level, and the max is GR150.
Let’s say a boss in a GR1 has 10,000,000 health.
In a GR150 the same boss would have 10,000,000 * (1.17)^150 = 168,997,103,799,869,030 health
Using the (1.17)^X rule, effectively you have to double your damage output to increase the GR clearance level by 4-5 levels. You’ll definitely be challenged.
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