As with any ranged ability, you can trace the path to your target however you would like. It doesn't have to be in a straight line. For instance, the Spellweaver could hit all of these hexes with this action by tracing the path along the red arrows.

Also note that this is a ranged attack, so any attack against someone adjacent to you has disadvantage.

Keep track of whether you consumed air when you used this ability by placing another character token on the card.

The top action, including the kill effect, is not targeted and therefore can be used on invisible enemies.

When the summon drops below 1 health, before it is removed from the map, it performs one last "Attack 3, target all adjacent enemies" action.

The top action does not specify a range so it is considered melee attack.