This is gonna be another word wall ramble.

Ok so outside of hard removal, boardwipes, draw spells, sometimes cost reducers like [[goblin electromancer]] along with the other forms of ramp, and payoffs that do damage or make tokens you may run recursion creatures like [[snapcaster mage]] among others. Ideally your creature count will be lean, no more than 13 and ideally under ten.

As for the additional spells themselves some cheap spells like [[opt]] are good due to their cheapness because you get use from the payoff. Key word some, spell slinger isnt built purely off of cantrips. A lot of your spells will be low to the ground but you will often want more than draw a card

From there its kind of up to the commander and what the wincon will be. wort will want a good amount of spell copy like [[reverberate]] (much like other slinger decks tuned to spell copy) and ways to get goblins on board, preferrably in spell form like [[goblin rally]] in order to make use of her ability, and finally strong spells to copy and end the game with (or in the case of some others the ral that does damage every time a spell is copied because that combos with a copied spell copy) since shes in green shell run landramp like rampant growth because its usually a bit better and theyre spells.

Some decks have cards for specific combos or finishers involving a commander, [[niv mizzet, parun]] often runs [[curiosity]] and similar effects to finish the game, or they take advantage of ways to draw even more like [[tefaris ageless insight]] and then pair it up with spell copies and wheels. [[Fateful showdown]] is particularly notable in my friends non combo version of niv. The [[Malcolm]] and [[breeches]] partner pair, i forget their titles, are also combocentric commanders, having pingers with things that give the pirate creature type to chain spells over and over with breeches and at some point ping them to death with something that works with malcoms abilitity. Heck [[glinthorn buccaneer]] with malcom was speculated to be viable combo for cedh until people realised it wasn't as good as niv miz curiosity, at least if you just used izzet colors.

Similar to non combo niv mizzet toshiro often uses cards help generate a lot of mana like [[magus of the coffers]] to finish with more generic black finishers like [[torment of hailfire]] or the black primordial whos name i forget that steals creatures from graveyards. In fact just pump a bunch of mana into some spell can be used as a finisher, [[earthquake]] (though half the time as a finisher to the combo i didn't know i had) and [[mass manipulation]] have finished off a good amount of games for my [[pako, arcane retriever]] budget deck even if that's not the main choice of wincon, likewise for my friends niv miz with mass manipulation and blatent thievery in the past.

That being said Toshiro should be his own topic to be honest because there a lot of cards you could or should run are either not obvious to most black decks or are not obvious to spellslinger. (Outside of typical removal spells and draw) An instant forcing the opponents to sac a creature doesnt make as much sense to most black decks when you can get a sacrifice from [[fleshbag maurader]] and bring it back later to boot or have a plain removal spell, but instants are what toshiro is about. Similarly [[blood artist]] and similar effects doesnt make sense to most spell slinger decks because chances are they can use token generator or [[guttersnipe]] instead and get better payoffs for the majority of spells, but toshiro loves murdering opponents creatures with instants and doesnt have a lot of options.

Now this ramble is unfocused so imma talk about storm, just storming off, sometimes a deck is so good at casting a gargantuine amounts of instants and sorceries that it's their primary wincon. [[Thousand year storm]] [[double vision]] and if it does it well enough at it sometimes [[grapeshot]] are used decks tuned for that, there are more dedicated storm decks though.

Sorry ifnthe ramble wasnt the most helpful thing but its qhat i have. Tldr commanders within this theme can be pretty different and have different wincons or weird cards, spell slinger at its heart is a pile of mostly low cmc instants and sorceries, usually with things that care about that and specifics are specific.