You need to set objective_kind_assemble_army, and in the parameters, instead of the artifact number, there should be an even number of parameters: the first, third, and so on – the IDs of the creatures, followed by their quantity.
I have the artifact that is given as a reward for completing the task, but I don't have the unit that needs to be brought.
Pictures below:

And also:

Please help! :smile45: Thank you for your answers!

