To expand:
- Mystic Visions run on a clock that starts when you watch the ad. Set an alarm to watch the next one ASAP.
- Chests: pay a few gems to accelerate your monster or hero wanted chests. These chests have a trickle of rare mats and are occasionally replaced by elemental chests with much higher odds of good loot.
- Titans: get higher grades against bigger titans. Read this post to understand why: Titans: Grades, Loot Tiers, and You
- check quests often (at least daily) to see if there is a Rare Quest up. These award rare mats for completing the last two levels. If you are really close to getting the final,level, consider paying 75 gems to continue, or just replay.
- same advice for finishing monthly Challenge Events.