POE Ruthless good prep for POE2?

I'd say yes, if you expect POE2 to be a bit tone down in speed and strength. Also it's good to detoxify your self from non-stop loot piñata and being a speed junkie in playing softcore speed gaming.

Ruthless is pretty much the testing ground for most PoE2 concepts.
While it's not really a good prep for the combat aspect you do get a good taste of what loot and player power might look like in PoE2 tho

So speaking from a position from someone who plays and really likes Ruthless, and who has only seen primary gameplay trailors and a TOUCH of the footage from Exilecon (i.e I'm not diving deep with streamers);

From what I see PoE2 has VERY little in common with Ruthless, in terms of it's tempo of gameplay or it's resource allocations. PoE2 looks a touch slower than 1, but early PoE1 wasn't all that face, that came as a result of years of possibilie combos adding up and the player base learning optimization tricks. I hope PoE2 stays on average slower overall (slower mobs, slower attacks, better telegraphs, slower players, and to a degree slower progression), but I'm sure the community will, as it is prone to do, find and focus on the fastest way to do anything.

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mnieradko wrote:

It's not like POE1 ruthless. It's worse, like ruthless + gauntlet x 100.

Sure.
By all means, play Ruthless until PoE2 comes out. You'll then find yourself in a fast paced game that showers you with loot.