Session Attacks are a type of attack in Tokyo Mirage Sessions ♯FE.
Session Attacks are special attack chains that are triggered by taking advantage of an enemy's weakness. If a character strikes the enemy with an attack the enemy is weak against, the other party members can immediately follow-up with a chain of Session Skills. Strengths and weaknesses are based on a combination of Fire Emblem's standard weapon types (Sword, Axe, Lance, Bow) and the elemental categories of Shin Megami Tensei (Fire, Ice, Electric, Force, Expel, and Death).
When the player is in the process of selecting a target for a chosen skill, the game's UI will indicate if a Session will trigger if a green exclamation mark appears next to the target Mirage's name. The UI also displays a Session lineup, indicating which characters will participate in the Session, in what order, and with which Session Skill. It also indicates whether or not a character's Session Skill in the chain will be effective or not, assuming the enemy's vulnerability or resistance to the skill's weapon or element type is known.
Session Skills are passive skills that each Mirage in the party can learn. These skills indicate the type of skill that leads into their own attack, and the type of attack that will result. For example, Ice-Lunge means that the the Session Skill is triggered if the preceding attack was an ice element attack, and the attack that will trigger from it is a lance attack. If the Session is to continue from there, the next character must have a Session Skill that triggers following the use of a lance Session Skill.
Sessions are subject to enemy resistances. If a party member uses a Session Skill that cannot damage the enemy, the chain will end. If the target enemy is killed during a Session and the Session is not yet complete, the Session will enter the Overkill state. When this occurs, all remaining attacks in the Session ignore enemy resistances. If Itsuki has learned the proper Radiant Skill, the Session will move to a new target if the original target took fatal damage before the Session completed.
Sessions can be extended by Duo Arts. Sometimes, a prompt will appear on screen while a Session is in progress indicating that the player can trigger a Duo Art. When triggered, the Duo Art will take place at the end of the Session and once complete allows for the Session to be extended. All characters that took part in the Session prior to the Duo Art will use a second round of Session Skills.
Enemies can also take advantage of Session Attacks against the player-characters. If a party member is hit with an attack that they are weak against, other enemies may follow up with Session Attacks of their own. Session attacks can also be evaded, and a Session will end prematurely if an attack misses its target.
At the start of the game, only characters in the active party can participate in Sessions. Each party member (other than Itsuki, who is always in the active party) is capable of learning a Radiant Skill that allows them to participate in Sessions, even when in the subcast. In Tokyo Mirage Sessions ♯FE Encore, three characters that are not full party members, Maiko, Barry, and Tiki, are able to participate in Sessions.
For each attack in a Session, there is a chance that a small bonus will be earned. This bonus may take the form of extra yen or material items. These bonuses are awarded at the end of battle with the standard battle rewards.