Shillelagh

Quote from Nihil_Keygain >>

The PHB says the range is Self, but Touch makes more sense.

 No, because that would allow you to enchant other people's weapons. The fact that letting go of it ends the spell tells you that the magic is coming from you, being channeled into the weapon. You are not enchanting the weapon. The range is self because you are the source of the magic. 

It says in the description that you "can" use your spellcasting ability instead of strength for your damage roll. Does that mean that you must?  Or is it more like Finesse where you can use either Strength or Dexterity?  Let's say I have a 20 Strength 13 Wisdom build but I want to get the force damage on my quarterstaff. Do I have to use the +1 to hit and damage from wisdom or am I still allowed to use the +5 from strength while benefitting from the damage die and the force damage?

Quote from XenogenX10 >>

It says in the description that you "can" use your spellcasting ability instead of strength for your damage roll. Does that mean that you must? 

No. "Can" means "can"; it doesn't mean "must". You can choose to use your spellcasting ability or the ability you would normally use for an attack with the weapon; presumably you'll choose to use whichever is higher. The damage type and die is a separate effect and occurs regardless of which ability score is being used for the attack.

There are effects that force you to use a different ability score for attack and damage rolls, like True Strike, but they have language like "the attack uses your spellcasting ability", not "you can use your spellcasting ability".

Thank you for the quick and precise response. Exactly what I needed to know!

Doesn't that mean that (d12) and (2d6) essentially do the same amount of damage? Except that on the two dice you can't get a one.

Quote from anwenmakepeace >>

Doesn't that mean that (d12) and (2d6) essentially do the same amount of damage? Except that on the two dice you can't get a one.

2d6 also has a different probability curve than 1d12 — all 12 possible rolls on the d12 are equally likely, but with 2d6 you're significantly more likely to get a result in the middle than either a high number or a low number. This effect is amplified on a critical hit where you're now rolling 4d6 instead of 2d12.

Also, having more individual dice leads to better odds of getting overall better results when re-rolling them via something like Savage Attacker, as well a greater increase in damage from things like Great Weapon Fighting that improve the values on individual dice. 

This spell and the reworked True Strike are kind of similar. Both let you attack with your spellcasting modifier, give you the option to switch what damage type you're dealing, and at higher levels may also increase your damage.

At a glance, True strike generally looks better. True Strike scales it's damage better at level 5+ when you can only make a single weapon attack, as it adds a D6 of damage at each cantrip upgrade level, while Shillelagh simply increases it's damage die size by one size (or effectively half a size at level 17), and True Strike can also be used with ranged weapons and thrown weapons.

However, there is additional nuance here. True Strike simply lets you make a single buffed attack as part of the action used to cast it. Meanwhile, Shillelagh buffs the weapon itself for a minute. Therefore, while you can't normally use True Strike to buff your opportunity attacks, you can benefit from Shillelagh during opportunity attacks, if you cast it earlier in the fight. And anyone with Extra Attack is likely to get more mileage out of Shillelagh than out of True Strike, as you can't use True Strike with Extra Attack unless you're a Bladesinger, Eldritch Knight, or Valor Bard. And even they may prefer Shillelagh, as if they're only using True Strike, only one of their attacks can be made using their Spellcasting modifier.

Granted, nothing is stopping a character with access to both (likely from Magic Initiate) from using both together. Though for those who can multiattack but can't sub in a cantrip for one of their attacks, True Strike is probably losing them damage. And for everyone else, they'll get more damage out of Shillelagh + Green-Flame Blade or Booming Blade, unless your DM doesn't allow legacy spells.

But True Strike is also available to Bladesinger, Eldritch Knight, and Valor Bard without needing a feat, unlike Shillelagh. And for Clerics using Divine Strike, they can get True Strike with just one feat, while Shillelagh + Booming Blade or GFB takes 2. Finally, For War Clerics, it's a pretty big toss up. True Strike can't benefit their bonus action attacks while Shillelagh can, but Shillelagh also takes a Bonus Action itself, meaning you'd be using your bonus action on one turn to buff any bonus action attacks you make on later turns