If you’d still like to use the Wowhead tooltips on your tumblr, go and edit your tumblr theme, add the Wowhead script tag in the <head> tag, then add the following code to the bottom of your template, before the </body> tag:
This bit of jQuery simply searches through the links on your page, and if they’re going to Wowhead, removes tumblr’s redirection which restores the tooltip functionality. Other links are unaffected; and as this is based on your tumblr template, this only works when looking at your blog, not when your posts appear on the dashboard. Here’s an example link: G’Hanir, the Mother Tree.
This is an awesome tip! Thank you!