An idea for a magic sword

[Zanthy1]

A sword (katana for coolest flavor) that appears normal but when swung has a reach of double its length (effectively +5 for DnD purposes). However that extra reach is from a seemingly invisible blade.

The function would be that the first 1d4 attacks made within line of sight of a target are with advantage (due to the target not being able to adequately determine the blades length and positionioning) but after 1d4 rounds (or attacks perhaps?) the advantage (from this specific source) goes away (representing the target having witnessed enough of the swings to determine the length of the blade). Would probably make it a +1 weapon as well.

What do y'all think?

[nickl_2000]

I think it is a cool function but keeping track of the attacks against a single person to know whether attacks are made with advantage or not would be a nightmare.

Make it rounds if you are going to do that.

[Man_Over_Game]

A sword (katana for coolest flavor) that appears normal but when swung has a reach of double its length (effectively +5 for DnD purposes). However that extra reach is from a seemingly invisible blade.

The function would be that the first 1d4 attacks made within line of sight of a target are with advantage (due to the target not being able to adequately determine the blades length and positionioning) but after 1d4 rounds (or attacks perhaps?) the advantage (from this specific source) goes away (representing the target having witnessed enough of the swings to determine the length of the blade). Would probably make it a +1 weapon as well.

What do y'all think?

It's a little strong, as it's strictly better than a +1 polearm.

I'd probably just make it be something like:

The first time you attack with this weapon, and all other attacks in the same turn, are made with Advantage.

Succinct, easy to understand, and no random number tracking.

A 1d4 has an average of 2.5. The average number of rounds for a combat is about 3-4. The average number of attacks from a Fighter (who will most likely use this weapon) is 2-3. So if you gave Advantage on all attacks in the first round, or if you gave Advantage on all the first attacks of every round, you're still giving about the same number of Advantage on attacks.

[Zanthy1]

Hmm those are valid points. What if instead it was treated like an illusion, with a DC 15 Int save? Passing the save makes it lose the advantage part?

[nickl_2000]

Hmm those are valid points. What if instead it was treated like an illusion, with a DC 15 Int save? Passing the save makes it lose the advantage part?

It's still more complicated and would require more work on your side to look stuff up.

Why not make it a resource instead. The blade is a spectral image, but 5 times a day the PC can make it be invisible for a round giving the PC advantage on all attacks until the beginning of their next turn.

It puts the tracking onus on the player, it makes it more active for the player, and it's a heck of a lot simpler for you.

[MrStabby]

For an illusory blade I would just say X times per day you can force an Int save (as illusion) or else suffer more damage. Simply for lower levels of bookkeepeing.

Or possibly as an alternative you can chose to force an int save instead of an attack (on a target that uses sight for sensory input) - less good against smart opponents but great against dumb ones.

[Haydensan]

For an illusory blade I would just say X times per day you can force an Int save (as illusion) or else suffer more damage. Simply for lower levels of bookkeepeing.

Or possibly as an alternative you can chose to force an int save instead of an attack (on a target that uses sight for sensory input) - less good against smart opponents but great against dumb ones.

I would go with something that involves an Int save as suggested, helps keep things in line with other illusions.

Something along the lines of:
"When you attack a creature for the first time each turn with this weapon, you can force the target to make an Intelligence Saving throw (DC tbd). On a success, the attack resolves as normal and is immune to this effect for the next *insert appropriate amount of time (first guess is 24hrs)*. On a failed save, attacks against the creature made this turn with this weapon have advantage."

There's probably a much less wordy way of putting it though

[SirGraystone]

That's an one hand polearm for those who want to use sentinel and no sacrifice the AC bonus from a shield.

[Galithar]

That's an one hand polearm for those who want to use sentinel and no sacrifice the AC bonus from a shield.

Except it's not a polearm, it's a sword. So the PAM attack when they enter reach wouldn't apply. So it has no benefit stacking with sentinel like an actual polearm would. If anything extending the reach without PAM makes sentinel weaker because they'll be further away (possibly, though not likely, close enough to hit an ally. If they were close enough why were they still moving?) when you stop them from trying to leave your reach.