I wouldn't think of being able to reach Silver II with having invested just in a Starter pack in the game and the rest just Daily Quests and Season rewards. But, I have strengthen some Splinters and while I thought Silver III was a great achievement, I have succeeded also reaching Silver II. In addition I have completed the Daily Quest at Silver level and got 5 great Reward Edition cards.
To sum it all, here are the achievements:
25 Reward Edition cards at the end of the Season
5 Common 4 Rare 3 Epic 2 Legendary monster in the battle
5 Reward Edition cards for Daily Quest completion
