Advance controls

Advance controls are actions that a player can execute. These actions include:

Flash Guard: Guard just as an enemy attacks to execute a 'Flash Guard.' Damage is nullified, and the SP and EXTRA gauges increase. Also, all attacks will be critical hits for a short time. This action debuted in Ys SEVEN.

Flash Move: Evade just as an enemy attacks to execute a 'Flash Move.' The party will be invincible for a time, and enemies will move in slow motion. This action debuted in Ys: Memories of Celceta.

Ys Wiki

Game Mechanics
Major Mechanics
Advance controls - Attack attributes - Attack bonuses - Cartography report - Currency - EXTRA - Gear - Journal - Landmarks - Party members - Raid Battles - Slay special enemies - Status Ailments - Unique Action - Warp
Removed/Replaced Mechanics
Boost mode - Buff potions - Bump System - Graffiti - Night exploration - Three weapons system
Others
Cameo - Dungeons - NPC - Playable Characters - Recurring Characters