Escalation is scheduled automatic change assignee depending on date/time based events.

Go to Process builder. Open Step Settings (1) and expand "Escalations" (2).

Click on "add" links (3) to open popup (4). Configure escalation.

Step can be escalated to (5):

• User, Group, Chatter Group, Role, Queue, Profile - should be selected from proper lookups or picklists.
• Fields - should be selected from the list of Data Source Object fields and should represent any assignable object (user, group, etc.).
• Variable - should be selected from list of variables defined in process and should contain ID of any assignable object (user, group, etc.).
• System (step will be proceeded automatically).

Escalation can be scheduled for some period of time relatively to specified date/time (event). Period (6) must be a numeric expression that should return a number of units that should be selected in proper picklist (7). Period type (8) picklist allows to select if period should be set before or after event.

Event is a some date/time value. User can select it's type (9) depending on his needs:

•   Process - event value (10) will be related to the current process instance:

• Field - event value should be selected from current process Data Source Object fields (click ">>" button to show field picker (11), select necessary field and click "Apply" button):

• Formula - value must be returned as a result of formula expression (click ">>" button to show formula editor (12), write a formula and click "Apply" button):

Check "Consider Business Hours" checkbox (13) to exclude non-working hours, weekends and holidays (if set in the user's organization) from date/time calculations.

To override standard chatter message check proper checkbox (14) and populate "Message" field (15):

Save configured escalation. All escalations will be shown in step properties. They can be deleted (16), added to library (17), or edited by clicking on proper row (18):