Gems of War

In the PvP section of the game, select one of the regions with a card restriction. I recommend picking a restriction where you can field a powerful team since you will likely try to get the other monolith achievement in the same run. The fifth and last fight boasts level 300 monsters/cards. If you can't field a team which can match this, beating all five battles will be difficult because unlike most other sigil based battles, it does not allow you to spend more to power up. This particular achievement is not so difficult because the starting battle has level 20 enemies.

Inside these regions there are monoliths which convey bonuses for PvP matches. Pick a monolith and win just one battle. If you are going for the five battle achievement, he difficulty will increase quickly. Mine capped at 300. As mentioned before, this particular achievement only requires one win, and it will pop as soon as you beat one battle.

For this achievement, I went with the green restriction region and the classic Essence of Evil team consisting of Essence of Evil, Queen Beatrix, The Wild Queen, and Leprechan.