The first time you hit with a melee weapon attack during this spell’s duration, your weapon rings with thunder that’s audible within 300 feet of you, and therefore the attack deals an additional 2d6 thunder damage to the target. Additionally, if the target may be a creature, it must succeed on a Strength saving throw or be pushed 10 feet far from you and knocked prone.
At Higher Levels: once you cast this spell using a spell slot of 2nd level or higher, the additional damage increases by 1d6 for every level above 1st.
Thunderous Smite 5e
- Casting Time: 1 bonus action
- Range: Self
- Components: V
- Duration: Concentration, up to 1 minute
- Scales: No
- Casters: Paladin
Actually, at the first time you are doing hit with the melee weapon attack at the time of this dnd thunderous smite spells duration and also your weapon rings with the thunder which ring sound would audible within 300 feet from you, and to the target, the attack would deal an additional 2d6 thunder damage.
Which brings me to my closing advice on this subject: player characters are capable of awesome things intentionally. No character can do everything, but every character can do a couple of things extremely well.
It’s less a saying about luck and pessimism and more a principle of product design. If two parts aren’t meant to “go together”, you design your product in order that they don’t. this is often why a well-designed product that needs assembly won’t have any connectors the proper size and shape to simply accept the incorrect part.
Whether they attributed it to Murphy or not, the designers of 5th Edition D&D followed this principle pretty religiously. If two parts of the sport aren’t meant to figure together–if two things don’t “stack”–then you’ll find it impossible to use them simultaneously, goodbye as you’re following the instructions for both of them literally.
If the druid keeps winning fights with an equivalent form or the sorcerer keeps blasting baddies with an equivalent spell, it doesn’t mean that form or that spell is overpowered.
Now, you’re right in your closing: smite spells don’t stack. All of a paladin’s smite spells require a bonus action to cast and concentration to keep up until they hit. So you can’t cast thunderous smite then cast searing smite and check out to hit an enemy with both of them. You couldn’t cast them within the same round, to start with, and if you are trying to cast one the round after you cast the other, you’d need to drop concentration on the primary one.
However, your player is true about the Divine Smite combo because while thunderous smite maybe a spell that’s cast using a bonus action before you attack, Divine Smite isn’t a spell and doesn’t require a bonus action it’s a category feature that needs no action and is used after you hit with an attack.
So to use both, you’d spend a bonus action to cast thunderous smite, and then use your action to require the Attack action, attack a target, and if you hit, invoke your Divine Smite. You’re following the rules for both abilities with no conflict between them, so it works.