If you're going to go into crafting --and especially if you're going to attempt crafting chakra-harnessing/explosive weapons-- there should be the chance to fail in meddlings and accidentally end up hurting yourself...possibly to a moderate degree so as to instill a sense of caution. Furthermore, there should probably be some sort of a mini-game attached to it, as otherwise you'll have people loading up on tons of explosive-tags, et cetera, and their use en masse could probably spark an end to the need for the majority of jutsu...and melee weapons...and most other tools in one's combat arsenal, now that I think about it.
The gist remains though -- if you intend to have high-power 'tools', there'd better be both a balanced/interesting/time-consuming method of production, as well as good costs and consequences for the production of said 'tools'. This would also increase the need for players to use such powerful devices *cautiously*, and not willy-nilly as many would assume, and it would also make the usage of these devices all the more critical during combat itself; A balance between power and utility should always be key in the design of weapons and techniques.
Other than that, yeah, I wouldn't doubt explosive-tags being in the game -- though I wonder, could there be the possibility of having different tag types? For example:
~An Explosive-Tag begins its fuse upon contact with an object (either by kunai or when applied directly...though a kunai is obviously far and away safer), requiring three seconds of burn-time before it goes off with a moderately-sized blast-radius (5-10 meters?)
~A Gas-Tag explodes in a billowing cloud of purple smoke treated with short-lasting nausea-inducing gas, requiring five seconds of burn-time before it goes off with a moderately-sized blast-radius that at first spreads (let's say an extra 5 meters for convenience) before dissipating entirely after ten-twenty seconds.
And of course, these different tags would then require different materials in order for them to even begin being crafted in the first place. In terms of mini-game crafting failure, the gas-tag would probably just exude its contents into the crafter's face, disorienting them for a few seconds -- while the explosive tag probably would end up exploding in your lap, causing a good enough amount of damage for the player to consider being considerably more delicate during the next round.
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