A Tap Sequence is a combat occurrence that may present itself during any fight. It has a chance of happening in situations such as fighting a dragon, parrying a titan attack or getting devoured by a Monstrosity.
When either Siris or Isa and the enemy lock blades, the word "TAP" appears in all caps at the center bottom portion of the screen, and the player must tap the screen rapidly. If, within a small time frame, the player taps the screen enough times, the player will break through the enemy's lock and the the titan will become stunned, thus giving the player an attack window. If the player fails to tap the screen enough during the time period, the titan will land a free hit on the player which cannot be avoided. Tapping the screen with multiple fingers increases the odds of success.
This sequence can also occur against monstrosities, in which the enemy will attempt to devour either Siris or Isa. The player must tap the screen to hold back its jaws, and failing to end the tap sequence in time will result in Siris or Isa being eaten. Unlike other enemies, small increments of damage are inflicted against the player's character while they are in the sequence.
Each success against tap sequences increases the difficulty of the next tap sequence. Regular non-Monstrosity titans will be more responsive and more likely to win the tap sequence. Monstrosity titans can clamp onto you for longer depending on how many times they have been expelled previously. After about three or four successful tap sequences, a non-Monstrosity titan will win future tap sequences very easily (multiple fingers tapping on the screen are required to even stand a chance), and a Monstrosity titan will be very tightly locked onto you.
When fighting a dragon, you may reach certain phases where the dragon performs specific attacks that force tap sequences, such as disarming the player's weapon, devouring the player or grinding and shaking the player with their jaw. Unlike regular and Monstrosity tap sequences, these cannot be avoided, but they do not increase in difficulty after successful tap sequences either. Various results of successful tap sequences against the dragon include incapacitating it (forcing the dragon to lay its head to the ground) for choice attacks or specified Slashes, Stabs or even automatic attacks to the dragon. Failing tap sequences with dragons is much like failing tap sequences with Monstrosities, with lack of reaction or speed resulting in either eventual or instant death.