Is that troll Cyrus making you mad? Do you tire of losing and just want to absolutely curbstomp your foes? Then worry not! Farming gems is an easy process in Stick War Legacy.

Setup:
1) Beat Normal Mode. This should take about an hour. DO NOT UPGRADE YOUR CASTLE HEALTH.
2) Replay levels and max out your Swordwrath to have LVL 3 Helmet and LVL 4 Sword. DO NOT UPGRADE YOUR CASTLE HEALTH.

Farming:
1) Select LVL 1 to be replayed.
2) Immediately order 1 Swordwrath and set your units to attack mode.
3) You will see two maxed-out Swordwrath sprinting towards the enemy side. Take control of the one in front.
4) Have the one in front guard as you continue to run towards the enemy.
5) There will be an Archidon that shoots at you. Block the arrows and run past it. The Swordwrath behind you will kill it with a jump attack. Simultaneously, kill a Miner with your jump attack.
6) The last Miner will retreat. Kill it with a jump attack.
7) Repeatedly jump attack the statue while your two other Swordwrath hack away at it.

In around 34 seconds (this is my average time), you will have earned 20 gems. This makes buying Arrow Storm, Miner Rush, and Griffith easy. :)