Kill Commander O'Neil

To complete this square you need to defeat Commander O'Neil, the field boss in Inner Aeonia. Wait until the "ENEMY DEFEATED" or equivalent screen appears to mark the square.

O’Neil is a field boss, available from the start of the game. It is usually considered a rushable and desirable square, as O’Neil drops 12,000 runes and a halberd.

The most common strategy to defeat him is to use the rot geysers near his arena, as the explosions deal damage to him. This strategy is not forbidden under the Elden Squares ruleset, provided you do not go up in the branches to avoid the boss completely.

Commander O’Neil counts as a Caelid/Dragonbarrow boss.