As mentioned in The Flame Leviathan Strategy & Tactics Guide, the formula for the HP bonus calculation of the vehicles used in this encounter was cracked.
How Vehicle Gear Scaling works
25-man scaling is same as in 10-man.
- Shirt, tabard, offhand, and ranged/relic slots do not affect vehicle scaling
- This does mean an ilvl 226 1 hand weapon is better than an ilvl 213 2 hander
- Enchants and gems do not affect it either, it is based solely off item level
- An ilvl 200 blue is equivalent to an ilvl 187 epic. Experimenting with other combos of blue/epic gear gave me reasonable confidence that a blue item is equivalent to an epic 13 levels lower
- An empty slot is equivalent to an ilvl 0 epic. This does mean equipping an ilvl 0 blue such as Insignia of the Scourge will be worse than having nothing at all in the slot
- Empirically, taking the average ilvl of your gear (subtract 13 for each blue, 26 for each green) and dividing by 15 (total number of applicable slots), then subtracting 170 will give you the percent increase of the health points of your vehicle compared to base - it cannot be decreased though (naked is a 0% increase)
- Thus: All ilvl 200 epic gear => 200-170 => 30% increase in vehicle hp. All 226 would be a 56% increase,
There are some limited testing of vehicle damage:
- Naked: 2148 average attack with 171 attacks average
- 213 gear: 3038 average attack with 160 attacks 3038/2148 = 41.4% so that seems to be within the margin of error for the expected value of 43%