Typhoon is a frontal cone ability, which means it will cast in front of you in a flat cone shape. The effect will only hit targets that are on your horizontal plane, meaning it does not shoot uphill or downhill.
The area typhoon affects increases width-wise as it travels away from the caster, meaning that typhoon will not hit targets that are to your sides but very close to you; however, because it is a cone shape, if a target is not directly in front of you, but is farther ahead of you, typhoon will hit that target.
Typhoon's range is misleadingly large and it is very easy to accidentally pull mobs or hit far away players that don't seem like they will be in range of typhoon. The most common way this happens is when people do not know that area typhoon affects widens greatly as it reaches its furthest point away from the caster.
Tips and tactics
Though similar to many spells, Typhoon is technically its own unique spell, combining effects and mechanics of other spells rather than being a mimic of a particular spell.
Typhoon can be used to knock enemy players and mobs off of any kind of ledge, including cliffs, boats, platforms, tops of buildings, etc. Typhoon will not knock players or mobs off of cliffs with invisible walls.
The knockback of this ability can be used to interrupt spells, but should be used early because:
Typhoon is an instant-cast spell, but it still has a travel time. This means that targets immediately in front of you will be hit the moment you cast, but targets far away will not.
Typhoon can be used in place of Hurricane if there are many mobs with low health or if other AoE is taking care of things in order to save a lot of mana in quick aoe situations.
Due to the daze effect it is often used to grief players on flying mounts while flagged such as in WG by knocking them off to their death for cheap and easy honor, or killing AFK players in the same fashion.