Spheres in Mage: Ascension overlap each other and even the core rulebook mentions that sufficiently creative player can solve every problem using nearly any sphere (except some specific situation, like accessing Umbra always needs Spirit).

However, that said, I had encountered numerous players that use out of game knowledge to justify their effects that seem to bypass everything but common sense.

The culprit player has a hermetic mage dealing mostly with Correspondence and Forces.

Example 1: He has no knowledge of Matter, but he tries to explain that indeed he has the capability of teleporting objects (that would regularly require Correspondence 3 and Matter 2) by means of temporarily making the space around the object be shared with target space, then undoing it in a way that leaves the objects at the target.

Example 2: He has no knowledge of Life, but indeed tries to stimulate a living being movement by controlling electrical signals in nerves - observing said signals first to get an idea.

Example 3: He has no knowledge of Matter, but rationalizes that indeed matter is energy, so he tries to perform a controlled reverse annihilation reaction to create a lead coin (and an anti-coin by default, composed of antimatter).

I tried to address those trials in different ways, but they all contributed to players frustration, because he believes that it was pure creativity that should be rewarded and not a game-breaking marysueism that is only possible because of his scientific background.

Ad 1: I allowed that, but increased Sphere requirement (Correspondence 3 to 4) and the difficulty (precise operation). He succeeded.

Ad 2: I allowed that, but decided that coherent control requires an exceptional success and that inevitably forced him to fail. He was quite upset.

Ad 3: I disallowed that, explaining that such a level of control is beyond his Arete. Furthermore, I asked the player if that is what his character believes, and if he is aware that the reasoning is technocratic in nature. He was upset about my refusal, but accepted the Technocracy bit. However, he did not stop nor did he roleplay this technocratic affinity in his character and took it as my personal vendetta when his avatar called him on that. I decided that this sort of magic is going to work only if I see a gradual progress of the character towards a technocratic mindset.

What to do when a player stretches and pushes his luck with spheres overlap, be it in a way described above or some other? How to prevent the player from mistaking pushiness with creativity? How to deal with players taking offense when I decide that their effect description is too far-fetched?

Spheres in Mage: Ascension overlap each other and even the core rulebook mentions that sufficiently creative player can solve every problem using nearly any sphere (except some specific situation, like accessing Umbra always needs Spirit).

However, that said, I had encountered numerous players that use out of game knowledge to justify their effects that seem to bypass everything but common sense.

The culprit player has a hermetic mage dealing mostly with Correspondence and Forces.

Example 1: He has no knowledge of Matter, but he tries to explain that indeed he has the capability of teleporting objects (that would regularly require Correspondence 3 and Matter 2) by means of temporarily making the space around the object be shared with target space, then undoing it in a way that leaves the objects at the target.

Example 2: He has no knowledge of Life, but indeed tries to stimulate a living being movement by controlling electrical signals in nerves - observing said signals first to get an idea.

Example 3: He has no knowledge of Matter, but rationalizes that indeed matter is energy, so he tries to perform a controlled reverse annihilation reaction to create a lead coin (and an anti-coin by default, composed of antimatter).

I tried to address those trials in different ways, but they all contributed to players frustration, because he believes that it was pure creativity that should be rewarded and not a game-breaking marysueism that is only possible because of his scientific background.

Ad 1: I allowed that, but increased Sphere requirement (Correspondence 3 to 4) and the difficulty (precise operation). He succeeded.

Ad 2: I allowed that, but decided that coherent control requires an exceptional success and that inevitably forced him to fail. He was quite upset.

Ad 3: I disallowed that, explaining that such a level of control is beyond his Arete. Furthermore, I asked the player if that is what his character believes, and if he is aware that the reasoning is technocratic in nature. He was upset about my refusal, but accepted the Technocracy bit. However, he did not stop nor did he roleplay this technocratic affinity in his character and took it as my personal vendetta when his avatar called him on that. I decided that this sort of magic is going to work only if I see a gradual progress of the character towards a technocratic mindset.

What to do when a player stretches and pushes his luck with spheres overlap, be it in a way described above or some other? How to prevent the player from mistaking pushiness with creativity? How to deal with players taking offense when I decide that their effect description is too far-fetched?

I use 2nd edition, but deliberately tried to be free of editions, as the problem for me is more related to struggling with the player's attitude (powergamer type, that likes to teleport bullets into brains and insists that it's not vulgar since the target dies before it is able to perceive the effect). Also, I'm waiting eagerly for MtA 20th Anniversary and would like it to work under that system as well.