I'm going to start off on a positive note. The idea behind reaper is a good one; players have been asking for more challenge for years, and at this point making elite more difficult (as was a commonly suggested solution) was unrealistic primarily due to the amount of complaining that would've generated.
That being said, there are things that I like about the implementation of reaper difficulty and things that I dislike. In this thread I'm going to focus on one particular dislike, explain the two main flaws within the decision to make the mechanic the way that it is, and propose a straightforward solution that I'm sure you (the devs) considered when discussing how to implement reaper.
Why reducing player damage output for reaper was not a good solution
Player damage output is reduced by roughly 92% in reaper 10. The goal of this mechanic was presumably to make it more difficult slash time consuming to kill monsters via straightforward damage output, which is something that it has succeeded in. However, this decision has resulted in
1) A system that changes the LGS ender set from overrated to extremely overpowered/undisputed best in slot
2) A system where effects that ostensibly increase your damage output don't actually provide you with any benefit
Since I assume issue #1 is fairly self explanatory I'm going to move right to explaining issue #2.
Reduction by percentage, low dice, and rounding
As we all know, spell power of the appropriate type increases the base damage of your spells of that type by 1% per point. If you cast greater ruin (base damage: 1000) with 800 force spell power, it'll do exactly 9000 damage (1000 + 8(1000)=9000), if you cast it with 801 spell power it'll do 9010 damage (1000 + 8.01(1000) = 9010) and so on.
I'm going to be using spirit blast as my sample spell, because (for better or for worse) a lot of people play warlocks right now and it has relatively low base damage. Please keep in mind that the issue I'm about to describe is applicable to ALL spells, although due to the nature of the issue it affects spells with lower base dice (and therefore lower scaling with spell power) far more than it does ruin (although even ruin can be affected). It should theoretically affect melee/ranged chars as well (in regard to melee/ranged power, additional damage stat, deadly and similar stuff) but I haven't looked at those numbers yet.
The issue is as follows: due to player damage being reduced in reaper, it is possible to get spell power that does absolutely nothing. For a spell such as greater ruin that has the highest base damage in DDO, that number is low. For something with low base dice, that number gets high very quickly.
See, it's largely due to the rounding that DDO has to do. The base damage of a spell is always a whole number, but when you get some spell power and multiply it by a percentage it often isn't. Spirit blast has an average base damage of 35 (10d6, average d6 damage is 3.5 x 10). With 10 spell power, you get 35 + 35(.1) or 38.5. Monsters in DDO take damage in whole numbers, so assuming DDO utilizes standard rounding rules the monster you're attacking will take 39 damage. CORRECTION: As per Geoff's post below, DDO rounds down to the nearest whole number, so you'd actually do 38 damage.
Any spell that does less than 100 base damage will require more than 1 point of spell power to deal more damage. In the case of spirit blast, in standard quests you'll need 3 more spell power to see a difference, and that'll get you about 1 more point of damage on each monster hit. 3 spell power is a pretty low number.
In reaper 10, that number jumps to about 33. Because it's always easier to show than tell, I've included line graphs showing the 100 spell power damage progression of spirit blast.
As you can see, the graph of standard spirit blast damage shows a fairly linear progression, although it isn't perfectly straight due to rounding. The reaper 10 graph demonstrates an abrupt, stepped progression where most of the time you gain spell power it isn't having any impact on your damage output.
Any mechanic that results in players being able to obtain higher "damage dealing" numbers without actually dealing any more damage is a flawed one.
The easiest solution is the obvious one
Instead of reducing player damage in reaper, increase the hp of the monsters. This will simultaneously prevent the LGS ender set bonus from becoming absurdly overpowered and allow players to continue to see noticeable benefits when they increase the numbers on their character sheets.
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I apologize for any grammatical errors/unclear sentences, it's hard to put in effort when you consistently get the feeling that no matter what you say nothing is going to change.
If anyone is interested, I'd be happy to post the tables from the above graphs and/or more numbers
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EDIT: Updated r10 sb damage graph to make it a bit more accurate