All the survival trials events this week, 2 each week from the monthly event, GNW packs (main source). If there's events that allows you to exchange for Seal Scrolls, you can do that, though I'd recommend you're betting off getting more power related items.

And since you're also f2p, pure determination is part of the recipe. ;P

I'm sorry what... How is that making fun?

I'm pure f2p (I can even take a screenshot and show you that 1st time Gaara recharge icon since Aug 2016 that is still there. And read my statement to him. "And since you're also f2p", implying that I am f2p as well) and I truly mean it when I say pure determination. I have almost 220 scrolls saved over months, and every time I open that treasure page, the urge to click Draw 10 is real. I'm not kidding when I mean pure determination.

The same goes with coupons saving as an f2p, pure determination if you want to get a certain ninja by saving up 10k+ coupons.

I haven't done any pulls for I think 3 months maybe? 3-4 sounds about right. 2 months is definitely too short, cause I don't get GNW packs every week (The leader will rotate the packs among the members).

And when I have the urge to Draw 10, I click on Bond Treasure, then I gtfo from that screen. :lol