[3.5] Paladin's Mount help

[LightningNinja2]

My group is having a level 20 tournament and I have decided to play a Paladin. the only thing I am having trouble understanding is how it's mount progresses. How it's additional HD work and what benefits it gains with them.

[SolioFebalas]

As paladin's mount table say, at 20th level your mount get +8 HD, +10 Natural armor, +4 Str, 9 Int (not a stupid animal), and bunch of abilities: Empathic Link, Improved Evasion, Share Spells, Share Saving Throws, Improved Speed, Command Creatures of Its Kind, Spell Resistance.

You may take Planar Substitution Level and you mount receive Celestial Template:
Smite Evil, Darkvision 60ft, DR 10/magic, Resistance to acid, cold, and electricity 10, Spell resistance equal to HD + 5 (maximum 25) (don't stack with existent).

Additional HD gives: 8d8 to hitpoints, +6 BAB, +4 Fort save, +4 Ref save, +2 Will save, (2 + Int modifier)x8 skills, 2 feats.

[Hytheter]

2 feats.

To my knowledge, you get a feat for every 3 Hit Dice, so depending on the mounts initial HD it might actually get three feats.
Eg a creature with 2 HD would have 10 as a level 20 mount. Since that passes the 3, 6 and 9 HD marks, he'd get three more feats.

I'm pretty sure that's how it works anyway.

[SolioFebalas]

I just wrote from the perspective of bonus HD and and since there are 8 and 8/3 = 2,6 ~ 2 (raw), mount receive 2 feats from BONUS HD. Ofcourse totaly them may be more based on whole HD/3.