For whatever reason, I sat down and created some hypothetical set bonuses for some equally hypothetical tier sets built for classes I have played at some point in the past. I get bored easily, you see. Maybe one day I'll get bored enough to draw them.

Anyway, just thought I'd throw them up.

Death Knight: Bereavement
  • Frost 2PC Bonus: Increases the damage of Howling Blast by 15%.
  • Frost 4PC Bonus: Obliterate and Frost Strike have a chance to trigger a Bereaving Strike, inflicting 60% weapon damage as Shadow.
  • Frost 6PC Bonus: Decreases the cooldown on Pillar of Frost by 15 seconds, and increases its duration by 5 seconds.
  • Unholy 2PC Bonus: Your diseases inflict 25% additional Nature damage.
  • Unholy 4PC Bonus: Your auto-attacks have a chance to cause your next Scourge Strike to consume no runes.
  • Unholy 6PC Bonus: Death Coil inflicts 25% additional Nature damage over 6 seconds.
  • Blood 2PC Bonus: Death Strike heals for an additional 10% for each of your diseases present.
  • Blood 4PC Bonus: Rune Tap heals for an additional 20% over 10 seconds and contributes to Blood Shield.
  • Blood 6PC Bonus: Heart Strike has a chance to make your next Death Strike consumes no runes.

Warrior: Doomed March
  • Arms 2PC Bonus: Your Mortal Strike and Overpower abilities have a chance to make your next Heroic Strike inflict 25% more damage.
  • Arms 4PC Bonus: Increases the duration of Colossus Smash by 3 seconds, and reduces its cooldown by 50%.
  • Arms 6PC Bonus: Your auto-attacks have a chance to make your next Slam inflict Shadow damage.
  • Fury 6PC Bonus: Increases the damage of Bloodthirst by 25%.
  • Fury 4PC Bonus: Grants Raging Blow an additional charge.
  • Fury 6PC Bonus: Heroic Strike inflicts 30% additional Shadow damage over 6 seconds.
  • Protection 2PC Bonus: Increases the duration of Shield Block by 2 seconds.
  • Protection 4PC Bonus: Battle Shout and Commanding Shout grant 12% additional dodge for 10 seconds after using them.
  • Protection 6PC Bonus: Whenever you take damage from a non-player source, you instantly restore 3% of your health over 6 seconds.

Paladin: Crestfallen Knight
  • Retribution 2PC Bonus: Increases the damage of Crusader Strike by 15%.
  • Retribution 4PC Bonus: Increases the Holy damage and critical strike boost from Inquisition by 15% and 5%, respectively.
  • Retribution 6PC Bonus: Templar's Verdict can be cast with 2 Holy Power.
  • Holy 2PC Bonus: Holy Shock heals all nearby allies for an additional 20% over 4 seconds.
  • Holy 4PC Bonus: Increases the healing of Word of Glory/Eternal Flame by 15%.
  • Holy 6PC Bonus: Each time Seal of Insight is triggered, you gain 2% additional Haste for 6 seconds, up to a maximum of 10%.
  • Protection 2PC Bonus: Increases the damage of Consecration by 15%.
  • Protection 4PC Bonus: Avenger Shield strikes one additional target and reduces all damage dealt by the affected targets by 15%.
  • Protection 6PC Bonus: Whenever Seal of Insight triggers, you receive a physical absorption shield that can withstand an amount of damage equal to 150% of the amount healed.

Hunter: Depthstalker
  • Marksmanship 2PC Bonus: Your Steady Shot ability has double the chance to cause Master Marksman.
  • Marksmanship 4PC Bonus: Increases the damage of Chimera Shot by 15%.
  • Marksmanship 6PC Bonus: Your Aimed Shot critical hits increase your Agility by 10% for 6 seconds.
  • Beast Mastery 2PC Bonus: Increases the duration of Bestial Wrath by 5 seconds.
  • Beast Mastery 4PC Bonus: Increases the damage of Kill Command and Arcane Shot by 15%.
  • Beast Mastery 6PC Bonus: Decreases the cooldown of Rapid Fire by 60 seconds.
  • Survival 2PC Bonus: Explosive Shot inflicts damage one more time and lasts one second longer.
  • Survival 4PC Bonus: Increases the damage of Black Arrow, Immolation Trap, and Explosive Trap by 10%.
  • Survival 6PC Bonus: Cobra Shot causes the Faceless Poison effect, causing each of your shots to inflict 5% additional Shadow damage. Stacks up to 5 times.

Priest: Last Sacrament
  • Shadow 2PC Bonus: Mind Flay has a 25% chance to refresh the duration of Shadow Word: Pain, and Mind Sear has a 30% chance to spread Shadow Word: Pain to all affected targets.
  • Shadow 4PC Bonus: Decreases the cooldown of Mind Blast by 1 second.
  • Shadow 6PC Bonus: The duration and damage of Devouring Plague is calculated as if you had one more Shadow Orb.
  • Holy 2PC Bonus: Increases the healing of Renew by 25%, and increases the healing of Holy Word: Serenity and Holy Word: Sanctuary by 15%.
  • Holy 4PC Bonus: While Serendipity is active, all healing is increased by 20%.
  • Holy 6PC Bonus: Prayer of Mending heals for an additional 30% over 6 seconds.
  • Discipline 2PC Bonus: Decreases the mana cost of Flash Heal by 10%.
  • Discipline 4PC Bonus: Whenever a party member protected by Power Word: Shield or Divine Aegis takes damage, they restore an amount of health equal to 5% of the damage absorbed.
  • Discipline 6PC Bonus: Whenever you heal a party member protected by Power Word: Shield, 25% of the amount healed is added to Power Word: Shield.

So yeah, there they are. Anyone else have any ideas for set bonuses?