Can the spell Freedom of Movement allow a character to escape a Forcecage spell?

Question

If a Warlock with the Trickster's Escape (Eldritch Invocation XGtE) uses his power to cast Freedom of Movement, would that allow him to escape a Forcecage?

Answer 1

No, Freedom of Movement does not counteract a Forcecage

Freedom of Movement has five principle effects:

• Target is unaffected by Difficult Terrain
• Target cannot have their speed reduced [by magical effects]
• Target cannot be Paralyzed or Restrained [by magical effects]
• Target can automagically escape from non-magical bindings using 5' of movement
• Target does not get disadvantage from underwater combat

None of these effects are consequences of the effects of Forcecage, which only creates a [magical] barrier that the creature cannot pass through. As a result, Freedom of Movement has no effect on a creature trapped by a Forcecage.

Answer 2

No.

Freedom of Movement doesn't give a creature carte blanche to move wherever it wants (e.g. through walls), it just prevents some specific effects (in addition to allowing escape from grapples and non-magical restraints for a cost of 5ft of movement):

• extra movement costs from difficult terrain
• reduction of speed caused by spells or magical effects
• the paralyzed condition caused by spells or magical effects
• the restrained condition caused by spells or magical effects
• penalties to movement or attack due to being underwater

A Forcecage does not reduce the speed of creatures inside it, and creatures inside of it are neither paralyzed nor restrained. Essentially, it's just a collection of six walls of force which happen to be arranged in such a way that it's really inconvenient for anyone in a 10- or 20-foot cube.