All classes that cast during combat will greatly suffer. Shaman will see a huge hit. Hell, even tanks like Paladin / SK. The mathematics of the proposed changes are pretty absurd, based on how it currently stands and Channeling skill's effect on rolls.
As it stands: If you start a cast and get hit mid-cast, you have to make a roll to succeed. Each subsequent hit during cast adds a penalty to your roll. This seems appropriately balanced for a non-classic server.
The changes would mean that every hit you have to perform a new roll. And you have to win ALL of the rolls in order to succeed the cast. I'm not sure how Channeling currently effects your roll chances, but let's say you had a 50% chance to win the roll. And you got hit 4 times between start of cast and end of cast. The probability of you winning all 4 rolls, at 50% odds per roll is 0.5 ^ 4, which is ~6%. If you got hit 8 times, the probability of winning all 8 rolls at 50% odds drops to ~0.3%.
Some things to consider:- Rune / Bedlam, etc does NOT stop spells from being interrupted. You don't take damage, but still have to win rolls to continue cast.
- As it stands, with 252 Channeling and level 60, fighting against a level 40-45 mob: I have recorded many instances of 3-4 hits in a round interrupting a cast pretty reliably with the current channeling mechanic. There have been times on my 60 Necro where a green pet with a torch has chunked me down 1k+ HP before I could get a root or Mez off. I've had to kite around to gain enough distance to cast 2.5s Screaming Terror or 1.75s Immobilize, just to make sure I don't get interrupted.
There is no guarantee that you will succeed a cast currently, even with max channeling, even at level 60, even vs. a mob that is 15-20 levels lower than you. There is a guarantee that past a certain number of hits, it will be probabilistically impossible to actually succeed a cast. (Granted, I used a simple example of 50% odds to win, which may not be representative of how the channeling skill weights rolls vs. NPC)
a) I'm not sure that's how classic worked. I'm dubious of the source of most of these "proofs" about how classic worked. It seems nilbog is relying on player logs to implement mechanic changes. I can understand at low levels this being the case - but at 60 with max channeling against a green mob, it should most definitely not be the case.
b) With all of the non-classic "QoL" changes made to this server - why nerf this when there isn't sufficient data to support it. Again, nilbog is cherry picking little pet projects to implement, but we still have rooted dragons, item links in chat, /makeleader, 7 day corpses, etc, etc, etc.
c) and furthermore, the channeling skill is not implemented correctly on saving throws currently. Maybe fix that first?