Blue: Magni is weak as a tank but he is a great addition to your team. That said, since you only have 2 telescopes ( you will need 6 to ascend him) you should hold off on investing in him for the time being. For Blues you should focus on Kiril and Grimm. Since you already have Gormek maxed (thumbs up) Kiril should be top priority. Thorne is useless so leave him where he is. Use him for now only on Green titans and war. When you get up to 5-6 telescopes (and 8 capes) you should get Magni going.
Red: With only 2 rings, you should also focus on your 4* heroes here. Level Scarlett first, but be on the lookout for Boldtusk. Once you’ve collected 5 rings or more, go for either Marjana or Elena. Both are great, but pick one and stick with it. One maxed is 100x more useful than 2 in progress.
Green: Kashrek is great as a tank on defense. For now that’s where you should put him. I’d level Hansel first then Melendor since you already have 2 healers and will be working on Kiril as well. Hansel is really a great 4* so be confident that this is a good use of resources. Leave Skittleskull where he is and only level him when you’ve run out of other heroes. Brienne is the top green 3* and possible the top 3* overall. She’s easy and cheap to level and is critical for performing well in the lowest tier of the monthly events. Do not eat her. Feed her when you get the chance.
Yellow: Other than Wu Kong, Yellow sucks at the 4* level. But Hu Tao sucks the most of all. Do not waste your orbs on him. Level Wu Kong ASAP. He’s the best 4* (maybe best 4 or 5*) in the game for titans and is solid on offense as well. After him, switch to Chao. If you’re feeling lucky and have some $$ to spend, do some pulls in the Guardians event and see if you can pull Guardian Jackal.
Purple: Rigard is awesome so you’ve done very well there. I’d work on Tiburtus next to give you color flexibility in the Ramming Pulverizer category (Gormek, Grimm, Tibs). Sabina is a good second purple healer so do her next.
Overall you have a great selection of 4* to work on. When you collect enough of the 4* ascension materials to switch attention to your 5* heroes, your team will be much stronger and more versatile than it is today.