I hope this place is right if not they can move it whereever it belongs. anyway i now started to understand that playing good riffs are much better than playing nonsense fast stuff so ive decided to learn some riffs that i can enjoy playing. I need some advices. I need riffs which not too easy but also not too hard. So can you recommend me some good melodic death metal kinda riffs or any other mid speed metal riffs?
Tool - Jambi

Good exercise too, can be hard but practice will get you there

If you are in dropped C check some SOAD, easy, but very fun to play