What is Silver in the game and why do I need it?
Silver is the main currency in the game. While Gold is what you mainly use to purchase minions in the battles, Silver gets you to purchase the actual cards. Although take note that you only get to purchase cards in booster packs -- meaning, you do not have control of what cards will be generated when they are opened. There is however another way to earn cards which you have more control of; Crafting. In any case, if your aim is to earn as much silver in the game, listed below are the 3 options on how to obtain it.
1. You can earn Silver mainly from playing PVP matches. Depending on the outcome of the battle (probably from garnering quests or for winning with minimal damage from your lifepool), you earn 25 to 50 silver per won battle in the game. However, losing a game will still get you 7 silver as a consolation.
2. Different online events also give you Silver along with special items which you can use in Crafting cards. This is rather practical in comparison to grinding for silver, as you can craft specific cards with these items. You may also salvage ink from multiple copies of cards which you do not need -- to similarly craft new cards out of it. Check the crafting section of this guide for more info.
3. When you play the game for the first time, log in daily for seven days to earn a bonus of 300 Silver per day. With each add-on pack priced at 1000 per pack, you get to purchase additional 2 packs of cards on your 7th day from just the daily bonuses.
Card packs are also obtainable via online purchase. They come in bulk (7 packs, 15's, 40's and 60's) priced as indicated on the image below.