When used, the Shadowbeam Staff will fire a purple beam which extends to its full length as soon as it is cast, including taking into account any changes in trajectory from hitting walls.
The Shadowbeam Staff may cause major lag issues when used with a special lighting option. Choosing another lighting option should fix the lag. It also causes a lot of lag when the Staff is used to cut through vines in the Underground Jungle.
The staff is very good for exploring dungeons because of the fact that the beam emits light, but it might also be useful to bring a Wisp in a Bottle.
The Shadowbeam Staff is the second-best magic weapon to use against segmented enemies such as Wyverns or The Destroyer (behind the Rainbow Gun) if fired along the full length of such monsters.
The Shadowbeam Staff is very effective combined with Spectre Armor, due to the mob-penetration ability, you do a lot of damage and you regain a lot of health due to the set-bonus.
The Shadowbeam Staff may be an upgraded version of the Water Bolt, due to the ricocheting effect and the fact you get it from the dungeon.
The Shadowbeam Staffs range is 114 blocks and underwater it is halved.
Worth to note that in underwater Shadowbeam Staff casts directly from character making it easier to kill close up mobs as above ground it is casted from the end of the wand which is about 2 blocks away from your character.