How to use a player's attack or spell attack bonus when using an NPC's attack

I came across this specific use case while setting up an NPC character sheet for a spell Area-of-Effect token that any player could drag from the journal.  I've searched this forum as well as Google using a variety of search strings and haven't found what I'm looking for. Any help would be much appreciated! The Character sheet that I'm suing is  D&D 5E by Roll20  and t he specific spell is the D&D 5E Druid spell "Nature's Wrath. I've set up the token and NPC character sheet the same way as I've set up other spell AOE tokens, but this spell has a few effects that I'd like to make into token actions attached to this particular spell token, that can be used by ANY player having a character with access to this spell. The spell itself does not include any of the following actions, forcing the player to roll them manually, which is cumbersome: Trees. At the start of each of your turns, each of your enemies within 10 feet of any tree in the cube must succeed on a Dexterity saving throw or take 4d6 slashing damage from whipping branches. For this action, I want to set up a macro that outputs to the chat a description the action, rolls 4d6 for the damage, and  displays the casting Character's Spell save DC . Describing the action and rolling the damage is no problem, but how do I extract and display the PC's Spell DC? Roots and Vines. At the end of each of your turns, one creature of your choice that is on the ground in the cube must succeed on a Strength saving throw or become restrained until the spell ends. A restrained creature can use an action to make a Strength (Athletics) check against your spell save DC, ending the effect on itself on a success. Again, displaying a description of the effect is easy, but again I don't know how to obtain and display the PC's Spell Save DC Rocks. As a bonus action on your turn, you can cause a loose rock in the cube to launch at a creature you can see in the cube. Make a ranged spell attack against the target. On a hit, the target takes 3d8 nonmagical bludgeoning damage, and it must succeed on a Strength saving throw or fall prone. For this effect, I again need to somehow extract and display the PC's spell DC as well as roll a ranged spell attack using the casting PC's spell attack bonus.

Hi Rick, For the D&D 5e by Roll20 character sheet it is: @{charactername|spell_save_dc}

Thanks, Gauss, but will that use the spell_save_dc of whichever player happens to be using the token action? IOW, say I have two Druids in my game:   Joe_the_Druid, who is 9th level, and Frank_the_Druid, who is 12th level. The player playing Joe_the_Druid casts  Nature's Wrath  and drags out the spell token, places it on the VTT, selects the token and activates the tree attack token action, which sends the attack description to the chat along with the result of the 4d6 damage and Joe_the_Druid's Spell save DC . In the same encounter, the player playing Frank_the_Druid also decides to cast Nature's Wrath  and drags a second copy of the same token onto the VTT and activates the tree attack token action, which sends the attack description to the chat along with the result of the 4d6 damage and  Frank_the_Druid's Spell save DC. Gauss said: Hi Rick, For the D&D 5e by Roll20 character sheet it is: @{charactername|spell_save_dc}

There are two options in that case, @{target|spell_save_dc} or set each player up with their own tree character sheet.  I generally select the latter option.  Alternately, if this is not a character, if it is closer to say, spiritual weapon, then I just have the player use an attack on their own character sheet.  As an aside, I don't see a D&D 5e spell called Nature's Wrath. Which book is it in? Edit: Do you mean Wrath of Nature? That isn't a creature spell, it is an area spell. where any trees in the area attack. It doesn't require tree tokens. 

Yes, the spell is Wrath of Nature, the area spell. The spell token that I created shows a 60 ft. X 60 ft. area of effect. The spell  has three different effects as I described, but those effects aren't automated within the spell like fireball or cone of cold . My main objective was to prevent the player having to make the die rolls manually. Thanks for your help!  I'll probably use separate tokens as you recommend, customized for each spellcaster.

So I do something with spells by using SpawnDefaultToken Mod . For example if I have 2 characters that can summon the same thing, I'll put the caster's save DC into a bar in the token. Like in this example I put it in bar 3: !Spawn --name|Spiritual Weapon (Selune) --offset|2,0 --bar3|@{selected|spell_save_dc} So each of those characters summoned the same spiritual weapon but I can put their spell save DC into bar 3, hence the 14 in one and 11 in the other. Then in the attack macro for the spawned weapon I can use the number in bar3. Gives me enough flexibility to have 1 summon template and use it for multiple characters.

Interesting solution Joshua.

Nice!