Shield Mitigation is a special trait which all shields share due to the nature of how the protective barrier is formed. As a shield is assaulted, computer systems automatically adjust its harmonics to match that of the incoming weapon’s fire. This has the effect of reducing the amount of damage done to the shield by completely negating a certain percentage of the enemy weapon’s attack. Once the primary shield has failed, emergency generators are brought online to maintain this last line of defense throughout the armor of the hull.
Shield mitigation is present in ALL units in game with shields, regardless of whether the unit has 1 shield point or 10,000. Shield mitigation decreases the damage received from all attacks regardless of source. Shield mitigation starts at a base of 15% and increases as more damage is accumulated. Abilities that directly damage hull strength (Ie. Jarrasul Evacuator's Nano-Disassembler) are not affected by shield mitigation. Shield mitigation is present even when the shields are down.
Shield mitigation starts at 15% and maximizes at 65% for capital ships and 60% for frigates. As capital ships level up, maximum shield mitigation increases by 0.0111 per level, which leads to a maximum reduction of 74.999%.
Because shield mitigation only increases after damage is done attacks/abilities which deal a large amount of damage are best used as opening attacks, only receiving the base 15% mitigation. Because of this and because normal shield mitigation caps out at 60%, slow-firing attacks that deal large damage like the Ogrov Torpedo Cruiser, can effectively 'ignore' some shield mitigation if used alone. E.g. if only 1 Ogrov is assigned to a target, its shield mitigation will max out when the missiles make contact, but then decrease by 25% in between attacks, resulting in only 35% shield mitigation.
Combating Shield Mitigation
In particular, with fully researched phase missiles, Vasari phase missile attacks have a 30% chance of ignoring shields and shield mitigation. Assuming attacks against a target with perpetual maximum shield mitigation of 60%, and a damage per shot of 10, your shots have a 70% chance to deal 4 damage (due to shield mitigation) and a 30% chance to deal 10 damage. Overall, your shots will deal 5.8 damage, a 45% increase to damage dealt. At 65% max shield mitigation, 55% increase to damage dealt. At 70%, a 70% increase to damage dealt, at 75%, a 90% increase to damage dealt. The effect is increased further by a Stilakus Subverter and its Shield Disruption ability.
Certain stars have a debuff called Gamma Exposure which negates Shield Mitigation by 10%.
"Alpha-strike" strategy is inflicting maximum damage before mitigation or regeneration can whittle away the stable DPS. The ultimate alpha-strike ability in the game is Snipe.