How to use multiple lines for messages?

[Agaloth]

Instead of:
one-participant: "&5&lDRAGON &8&l» &d<killer> &7just defeated the &dEnder Dragon&7!"

Is there a way to do multiple lines like this:

  one-participant: 
  - '#FEEF00⎥'
  - '#FEEF00⎥     #FE7500&lDragon'
  - '#FEEF00⎥     &d<killer> &7just defeated the &dEnder Dragon&7!'
  - '#FEEF00⎥'

[evs-dev]

You can enable custom-commands and add, for instance, a /tellraw command for each line you want.

[Agaloth]

What about the placeholder though

[evs-dev]

Placeholders can be used in commands. See the comments in the config for the exact details.