The actual equation actually works out close to the same format as the current one:
Mastery: Primal Tenacity causes the Druid to gain a Physical absorb shield equal to 16% of the attack's damage when they are hit by a Physical attack. Attacks which this effect fully or partially absorbs cannot trigger Primal Tenacity.
Garrosh melee's Tova for 200 000
Tova gains Primal Tenacity (50000 absorb)
Tova gains Tooth and Claw
Tova casts Maul
Garrosh receives Tooth and Claw debuff (reduces next melee attack by 160 000)
Garrosh melees Tova for 40 000 (Not enough to break my Primal Tenacity shield 5000 left)