Riftwalkers need to keep this spell running constantly, or their entity will take multiple times the damage it normally would from most sources and suffer other drawbacks. It will also be unable to use its skill.
Learning how to keep this spell from dropping is one of the fundamental skills a riftwalker needs to develop to succeed in the guild.
The in game help reads:
No saving throw. Casting time: 6 rounds. Type of spell: neutral spell. Affecting stats: wis. Cast type: rift. Spell point cost: 152. Before you can command your entity to use skills (gem cmd use <skill>), you will need to have control over your entity. This spell will establish a link between you and your entity, allowing you to command it. Without this bond your entity will be very weak and vulnerable. This spell uses 1 rift spark.