If I recall, the ignots were introduced when they started the Season stuff. Like you, I basically just toss them into Merlin's cauldron for the daily task. But you can throw them, plus other things like concessions and decorations to turn into elixir. Before the change in the happiness and Season Pass, I would get the elixir and spend it to keep my happiness at the highest level each day. That feature is gone though. However, you can use elixir to purchase things in Merlin's shop. The upgrade scrolls and character tokens are an example of that. I have also used elixir to purchase some of the attractions that are not part of the various events, but are made available to everyone. I think Spaceship Earth and Jungle Cruise are examples.