When defending, the player can use the touchscreen to drag around an outline of a shield on the screen, to protect the player character from incoming enemy attacks, and when attacking, the player can draw a line on the screen across an enemy, mimicking a sword slash. When using magic spells, the player needs to draw an arcane symbol on the screen.
This describes a game mechanic where the player uses their touchscreen to interact with the game world. The actions of defending, attacking, and casting magic spells are all visually represented through drawing shapes or symbols on the screen.