Hey, hoping to get a bit of advise on this. I’m a very C2P player, (basically F2P) with only 2 5* heroes in my roster, both green; Evelyn and a just pulled Lianna. Both very good heroes, however I currently have leveled Buddy to 3*60. Do I ascend Buddy all the way and lose my sturdy shields? Or hold on until I get enough feeders (and mysterious tonic, I only have 3) to ascend one of the 5* greens?
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Buddy. 3 more tonics could mean at least 6 months in the meantime you will have a lot of those shields.
I say finish Buddy. He is pretty awesome and you can throw presents at people all year round.
Theoretically you will get 2 Shields per tonic so using this you will have 6 by the time you get your 6th tonic.
Get the 5 stars to 60 at least while you wait after Buddy.
First of all congrats on both Evelyn and Lianna!
I agree on Buddy. Typically you want a full rainbow team (or two!) of 4* before you start diverting your ascension mats to 5*, because 5* takes a lot more:
(The 5* requires all the same-color items across the page, not just the right-hand column!) 
You can more or less level two 4* for the cost of one 5*.
How are you doing on Rare Quests? They pop up every 7-10 days, giving s/he who completes them all Rare mats in roughly seventy days, or 36 mats each of 3/4* every year (see pic above).
Remember the game gives you mats from a variety of places: Titans, Rare chests, war chests, Mystic Vision, Rare Quests, etc etc. You will have plenty of you are diligently searching.
Thanks for the info. Yes Im hitting every quest, war, titan, etc that I can. Have mystic rings and orbs out the wazoo right now, just lacking in Tonics.(and low on shields of course…)
I find that the ascension mats shift over time…right now I keep getting magic orbs, but very few sturdy shields, etc. Keep collecting, you WILL eventually use them all!
Congrats! You’ve got a great start on some awesome heroes. I agree with Buddy. It’s hard to wait to feed those 5 stars but it’s faster to max up a 4 star.
Be patient, enjoy the journey and don’t compare your roster with other players. Some (like me) who have (now had) been a free to play player for 16 months, or a player with deep pockets, will have more heroes than you.
With time, you will have a full roster too.
Thanks for the advice. Yes, Ive come to learn the patience game with E&P that’s for sure. And I do already have some great 4 stars with emblems so I am quite happy with what I have . Its always that moment of indecision with mats etc, and what to do when you’re limited.
Even very long-time players still ask, so keep asking. The answers benefit the rest of us, too.
A useful rule of thumb: you’ll likely get 3 sturdy shields per tonic (and 3 orbs per dart, etc.). You’re lacking 3 tonics, somyou;re likely to gain about 9 shields while you complete the set—which is more than you need to ascend a 5*.
I would hold Evelyn at 3/70 and take Lianna to 4/80. Evelyn is there for her special, while Lianna is there for the kill.
I’m exactly the same, had Orbs for fun at one stage, still have enough to ascend another 4* yellow but I’m going to wait for better heroes.
At the moment I can’t find sheilds anywhere!
Yet they will come. Trust me. I have a ton of ascension mats over time, even after leveling a number of 4* and 5*. 
I’d finish Buddy first. As others have said, it will be less resource and time intensive, plus he’ll be very useful for you during the (presumably) long time it will take to gather the rest of the needed materials.
Then I’d work on Evelyn. Her special will combine nicely with Buddy’s to dramatically improve your scores against blue titans, while shredding any blue tank you raid. Take her to 2.60, or 3.70 if you can.
Then Lianna. She will be a killing machine, especially since you will already have Evelyn ready to work with her. I think that’s the best combination of having the appropriate power (based on facing progressively harder titans and enemies in raids) when you need it.
Edited to add:
Actually, now that I think about Buddy’s defense down, I could see that being enough to synergize nicely with Lianna. So now I guess I’m torn. Either is a viable option and you’ll want them both eventually. But my first reaction was Evelyn. It’ll be interesting to see if anyone else voices an opinion.