<div class="col-12">
     <%= f.input :saving_throws, collection: ["Strength", "Dexterity", "Constitution", "Intelligence", "Wisdom", "Charisma"],
          label: "Saving Throws", input_html: { class: "saving-throws-select", multiple: true } %>
</div>

$('.saving-throws-select').selectize
    delimiter: ","
    persist: false