Any Suggestions for Balancing My New Ninja Trick?

[Kite403]

My group and I are doing a campaign set during an alternate universe of the Warring States Era in Japan. One of the players, being a fan of Naruto wanted to be able to do ninjutsu. SO being the nice GM, I bulls**ted something together and made it a Ninja Trick.

Basically, by spending Ki points, a Ninja can use a spell from the elemental wizard's spell list. The cost is equal to the spell level. A Ninja can only use those spells that he has learned and he can only learn as many as a sorcerer of equal level divided by half (rounded up). All the DCs are run off Charisma (since the Ki Pool runs on it).

For reference, the Ninja in question is 7th level, has 20 Cha, a Ki pool of 10 (thanks to Extra Ki feat), and knows 1 3rd spell, 2 2nd, 3 1st, and no 0-level.

Our first game was last night, and from what I could tell, he had a lot of fun with it. He even defeated the ogre mage "boss" as the other party members forced him to take flight with a well-aimed (and SR-beating) Fireball. He caught two buildings on fire with it in the process, but overall I felt he made the most of his new trick without it breaking the game. Anyone think this could lead to trouble down the road?

 

[gamerprinter]

Ki is supposed to be the source of any 'magic' for the ninja, and among ninja tricks is the ability to cast a cantrip or a 1st level spell, if already possessing the cantrip casting trick. The advanced trick isn't available until much higher level. With this in mind, I don't think allowing a ninja to cast anything higher than 1st level is balanced. A ninja is not a spellcaster, so should never get anything more powerful than a first level spell. You want your ninja to cast spells? Then multiclass with a spellcaster, any other way is unbalanced.

As the primary developer of the Kaidan setting of Japanese horror (PFRPG), I had intentions of including a lot more varied ninja tricks that emulated more spells, but this was before Paizo's development of the Qingong Monk, which is very similar to what I intended. So if you allowed your Naruto ninja to gain access to all the ki powers available to the qingong monk, you'd have a rather spell-casty ninja.

But anything more powerful than that - like being able to cast fireball, I don't think would be ever be appropriate nor balanced. A martial class should never be able to emulate a 6th level spellcaster spell, doing so is totally breaking the game.