Hi All, so I've just started DM'ing tomb of annihilation and my fighter (new to DnD)  has expressed interest in using special ammunition for his croasbow. For example an arrow with a small explosive attached. I don't want to strictly say no as I don't want to stifle my player's creativity and interest in the game. He is also the only non-magic user in the party so I'd be happy to give him limited access to something like a 'magic' explosive arrow but have more of a mechanical or crafted feel to it. Have any of you homebrewed up something similar or different?

My thoughts were to make it a +1 arrow with additional +d6 fire damage with a 10 ft radius. My thoughts were to make this reasonably expensive to buy or craft. But I don't necessarily want to bog down the game with a lot of crafting etc (I'm happy to do this if the player/s want crafting). One of the merchant princes sells +1 arrows so i was thinking about modifying her stock list. The  party managed to 'fix' the dinosaur race and won a lot of gold, but that's a hilarious story for another post (that was a fun session to DM :D ).

I'd just use the rules for alchemists fire (flask) and basically treat the crossbow like a grenade launcher.

EDIT: So basically your fighter gets his normal arrow damage, but also gets the fire damage each turn from the explosive.

Awesome, thanks :)

Alternatively.... grenade, fragmentation