Spend keys and gems on rotation 2. Use pity to target S-tier gear from other rotations. Plague gloves from rotation 3 is usually the pick.

Where to spend your resources for maximum progression.
Spend on seasonal chest 2, and use pity to get S-tier gear you need from other chests.
Spend at most 25k gems on fishing. Aim for 12 coins (2 gear select chests) or 15 for a legendary / random legendary hero.
Best spent on shovel to obtain rose or raven faster from the shovel event. Alternatively, spend on legendary keys.
Unlock the Aura first, then focus on either Shards or Legendary Keys based on what you need.
Quick wins and common mistakes to avoid.
Dealing with enemy types
Poison / Freeze / Burn
Spike
Buff Steal
Vamp
Dodge
Stun
Seal
General tips