Placeholder support for the shield mechanic.

Summary

At the moment, the shield mechanic doesn't support placeholders. It'd be a great addition to the line-up to be able to use placeholders here.

Usage

As with the placeholder supporting skills, it'd be used as followed: - shield{amount="<insert_placeholder_here>"} @target

Value

It allows for variety in the skills, which is increases the usage of the skill.

Priority

I don't think is should have priority over larger features, as it's more of a quality of life tweak.

Implementation

Essentially the same as the placeholder supporting mechanics, I'm not sure how it's implemented in the back-end, so I can't comment on that. However the usage is the same as similar skills.