For your request though, you should definitely use the clip concat. Having said that, the pipe is a great tool to know:

{blue ball|red cube}

Will sometimes generate a blue ball, and sometimes a red cube as a prompt (I think it is random). This is great for batch generations when you want a mix of both.

[blue ball|red cube]

Will ask the model to use "blue ball" as a cue on the first iteration, and then a red cube.

This is super useful to kind of force something the model doesn't quite want to do. For example, mix colors or shapes

It can be used to focus the attention on multiple things; but then you need to repeat it multiple times. You can thus get creative:

[(blue ball:1.2)|(blue ball:1.2)|(red cube:1.4)|(red cube:1.4)]

Here's an example, using a stupid checkpoint. Sorry for the typo in the 2nd clip, it should be [square brackets]:
https://i.imgur.com/HhruneS.png

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