Grappling Hook

The Grappling Hook is an incredibly useful and practical tool, used to grab on to surfaces and is created with 3 Iron Chains and 1 hook. As of Patch 1.1 it can also be bought from the Goblin Tinkerer for 2 gold each, making it available to all characters who have found him. It can be used on all solid surfaces and is helpful for navigating caves and building homes as you can use it to cut vegetation.

It does not need to be placed in the hotbar to be used as it has a designated hotkey, (default is E) and, after pressing, the grappling hook will be fired in the direction of the mouse. However, it does have a limited range.

You may use other tools at the same time as you are grappled onto a wall, but note that destroying the block you are attached to will break the connection causing you to let go and fall. As of the 1.0.6 Patch, the grappling hook does not have a time limit when grappled to any blocks.

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The Grappling hook does not damage monsters as of the 1.0 Patch, and instead pass through them.

Grappling hooks can be used to pass through a chokepoint that you would not normally fit through. The endpoint still needs to be at least 3 blocks high and 2 blocks wide, but you can pass though a more narrow gap to get there. As an example, face left in a three block high, horizontal tunnel. Dig the two blocks above your head on the left, and the three to the left of that, starting with your head level, and the two above. You will not be able to jump through that gap, but you can grapple through it.

The grappling hook is an absolute necessity for mining and trekking, and is a massive help as it helps players reach heights and areas otherwise impossible to reach. Players can also use it for quick escapes from water and mobs alike. As an added perk, by firing the grappling hook at the ground while falling, fall damage can be negated; however, it should be noted that the grappling hook should be fired about 2 seconds before impact, or else the grapple will not hit the block before you do.

An upgraded version of the grappling hook called the Ivy Whip can be crafted from the grappling hook and items found in the Underground Jungle.

Also as of 1.1 there is a dual hook which is a drop from mimics, which is a bit like an upgraded grappling hook because you can shoot out 2 hooks at once. This is useful because if you are falling and you miss with your first shot, you have one other shot to save yourself. This can make climbing holes a lot easier.

Trivia

 * The tooltip refers to a line that Scorpion, a recurrent character in the fighting game Mortal Kombat, shouts just before impaling his opponent with a grappling hook.
 * You can cancel falling damage with careful use, by firing the Grappling Hook at the ground while falling. This can be done with the Ivy Whip, and Dual Hook too; though with all three it requires good timing.

Update Info
1.0.6 - No longer has a time limit of 60 seconds