I haven't noticed any imba in the combo of Offense/Defense with mark/reinforcements, but then again, your Offense effects (only 10% in original) and Defense effects (up to 100%) are boosted; if they are cut back again, they will most likely only be somewhat effective in combination with mark/reinforcements, while remaining own-of-their-kind hopeless on their own.

That's exactly what I'm saying: either it's imba in a combo, or useless individually. And that is not good.
Take the same devilish (x2 damage). Let's say it's normal under ordinary conditions. But what happens if you take the mark of the cursed after it, which is also normal on its own? Effectively, the efficiency of the mark will be boosted more than twofold (the same half-turn is spent, but the effect is twice as powerful). It results in a practically mandatory combo, since one perk boosts another by more than 2 times.

Added after 17 hours 59 minutes
Update:

ATTACK (10/20/30%)
1) Cold Steel -> Battle Frenzy (without penalties)
2) Marksmanship (30%) -> Attacking Style (every hero on the battlefield receives +3 Attack)
3) Tactics -> Haste (orcs receive +1 Initiative)

Fire Arrows removed. Retribution moved to Leadership.

DEFENSE
1) Fortitude -> Endurance (+10% Health)
2) Evasion (30%) -> Defensive Style (every hero on the battlefield receives +3 Defense)
3) Readiness -> Stone Skin (orcs receive +2 Defense)

Turtling removed. Reflection removed. Fight to the Last moved to Leadership.

LEADERSHIP (unavailable to undead)
1) Inspiration (50%) -> Retribution
2) Troop Rally -> Fight to the Last
3) Diplomacy -> Empathy

Troop Rally: for every 3rd hero level (including previously obtained), creatures of levels 1-3 join them (+3/+2/+1).
Diplomacy: whenever neutrals flee the battlefield, the hero gets the opportunity to buy up to 30% of the creatures (at 100% price), but not more than a total of 500 gold per hero level.
Treasury removed. Speed Aura moved to Logistics.

LUCK (+50% lucky damage)
1) Soldier's Luck (additional +1 Luck) -> Critical Luck (+100% lucky damage)
2) Magic Luck (variable mana, additional +1 Luck) -> Sorcerous Luck
3) Resistance (magic) -> Double Resistance (dwarf luck)

Luck on the Road removed. Trophies removed. Ashi's Patronage removed.

LOGISTICS
1) Scouting -> Stealth (silent pursuer)
2) War Path (pathfinding, additional +1/+1 Attack and Defense in foreign lands) -> Looting / Speed Aura
3) Unraveling Mysteries

For scouting, the hero additionally receives +1 random minor artifact for every 5 levels (including previously obtained).
For stealth, the hero additionally receives +1 random major artifact for every 10 levels (including previously obtained).
Looting: additionally, enemy hero troops receive a -1 speed penalty (does not work against neutrals).
Navigation removed. War Path (original) removed. Death's March removed. Sharp Mind moved to Sorcery. Surprise Attack moved to Avenger (elf racial).

ENGINEERING (machines)
1) Ballistics -> Rapid Fire
2) First Aid -> Plague Tent
3) Artillery -> Elite Machines (runic machines)

Engineering: x2/3/4 machine health and +1/2/3 Attack for shooters per wagon.
Ballistics, First Aid, Artillery do not double the health of corresponding machines.
Tent healing and ballista damage do not depend on engineering level. Ballista damage grows from Attack + Knowledge, tent healing - from hero level.
Artillery (catapult): before a battle in an open field, kills 10% of enemy creatures (rounded down).
Sulphur Rain removed. Earthshake removed.

EDUCATION (unavailable to orcs)
1) Distraction (30%) -> Counterspell
2) Intellect (magic attraction, 40%) -> Academic Style (every hero on the battlefield receives +3 Knowledge)
3) Scholar -> Mentorship

Education gives +2/4/6 random stats regardless of hero level.
Scholar: additionally, the hero learns 1 random spell of levels 1-2 for every 2nd level, including previously obtained.
Dark Revelation removed. Keeper of Secrets removed. Unraveling Mysteries moved to Logistics.

SORCERY (unavailable to orcs)
1) Mysticism (mana replenishment) -> Secret Knowledge / Elite Casters (secrets of light)
2) Wisdom -> Casting Style (every hero on the battlefield receives +3 Spell Power)
3) Sharp Mind (30%)

Variable Mana moved to Luck. Distraction moved to Education. Counterspell moved to Education. Secret Advantage removed. Secret Revelation removed.

WAR CRIES (available only to orcs)
1) Mysticism (mana replenishment) -> Secret Knowledge / Elite Casters (secrets of light)
2) Rage Cry
3) Mighty Cry

Distraction moved to Education (unavailable to orcs).

LIGHT MAGIC (unavailable to orcs)
1) Master of Wrath -> Storm Wind
2) Master of Blessings -> Eternal Light (additional +regeneration)
3) Master of Protection -> Seal of Light (additional +holy word)

Fire Protection removed. Twilight moved to Counterstrike (human racial). Secrets of Light moved to Sorcery.

DARK MAGIC (unavailable to orcs)
1) Master of Pain -> Cursed Land
2) Master of Curses -> Darkness Weakness (additional +sorrow)
3) Master of Mind -> Seal of Darkness (additional +unholy word)

Dark Replenishment removed (critical bug). Tormenting Strike moved to Occultism (dark elf racial).

CHAOS MAGIC (unavailable to orcs)
1) Master of Fire -> Pyrokinesis (additional +fire wall) / Mana Burst
2) Master of Ice -> Deadly Cold (additional +stopping cold)
3) Master of Lightning

Secrets of Chaos removed. Magic Exhaustion removed. Fire Fury removed.

SUMMONING MAGIC (unavailable to orcs)
1) Master of Earth (additional +earthquake) -> Fog Veil (only -30% Initiative)
2) Master of Life -> Heavenly Shield
3) Master of Elements (charms) -> Elemental Balance (additional +elementals)

Banishment removed. Exorcism removed. Fire Warriors removed.

DEMONOLOGY (available only to demons)
1) Wide Gates -> Fast Gates / Reinforcements (until the end of battle, the number of creatures in the hero's army increases by 10%, rounded down)
2) Hellfire -> Withering Flame
3) Corpse Devourer

Fire Retribution removed (built into Hellfire). Exploding Corpses removed (built into Corpse Devourer). Mark of the Cursed moved to Occultism (dark elf racial). Lucky Gates removed.

RUNES (available only to dwarves)
1) Attacking Hird -> Runic Harmony
2) Defensive Hird -> Runic Recoil
3) Completed Rune -> Updated Rune

Greatest Rune removed.

AVENGER (available only to elves)
1) Enchanted Arrow -> Enchanted Ballista
2) Deadly Shot -> Rain of Arrows
3) Forest Fury -> Surprise Attack

Forest Cunning removed. Forest Leader removed. Native Lands removed.

COUNTERSTRIKE (available only to humans)
1) Double Strike (devilish strike with 100% chance) -> Oversight
2) Prayer -> Twilight / Guardian Angel
3) General (automatically trains (promotes) creatures depending on Counterstrike level: 3 militia / 2 archers / 2 swordsmen / 1 monk for every hero level, including already obtained)

WRATH (available only to orcs)
Blood Memory -> Battle Euphoria / Fire of Rage
Reinforcements -> Stunning Strike
Goblin Help

Protect Us All removed.

OCCULTISM (available only to dark elves)
Assassin's Mark (mark of the cursed) -> Tormenting Strike
Dark Ritual -> Fallen Knight (will be renamed)
Enhanced Magic (Arcane wave) -> Sense of Elements

NECROMANCER (available only to undead)
Banshee Cry -> Death's March (-1 Luck to enemy troops, -1 Initiative to enemy hero troops)
Eternal Slavery -> Lord of the Dead (+mummies) / Harbinger of Death (+death knights)
Spiritual Link

ARTIFACTS (available only to mages)
Magic Mirror
Wizard's Mark -> Metamagic (+1 Spell Power and Knowledge for each expert school of magic)
Artifact Absorption -> March of Golems / Machine Loyalty (additional +1 Morale)

Mastery over Machines removed.