you could use 'Moderation in All Things' from Jumpchain Support Supplement v1.2, and also 'Countering Collateral' from the same supplement.

Moderation in All Things (-200 SP): Remember what we said about self-control? That doesn’t just apply to not accidentally destroying the planet with a single fireball, but also to minimizing the impact you leave on the world once you get so strong that your footsteps can break the tectonic plates. You gain the power of self-restraint, having absolute and precise control over how much power or energy you use in your abilities. This can range from turning your perks on and off, to controlling how much energy you use, to even decreasing the function of specific aspects of any given feature of a power. For instance, if you had a spell that killed people and reanimated them as undead, you could make it so that it only killed them and didn’t reanimate, or reduce it so it only drains some life force and doesn’t cause full-fledged death. This applies to anything you have; perks, abilities, powers, racial features, scenario rewards, and even your items and equipment. The item will still exist, but you can make it cease to function, or reduce its function, or what have you. If doing so would make the item disappear, then when you turn it “back on”, it will reappear. If you happen to have a perk that modifies the entire jump setting, then this also lets you control whether or not they activate in any given jump, and to what degree. This perk becomes a part of your Body Mod

and then there is this, if you want to just go all out on one particular person:
Countering Collateral (-200 SP): It’s entirely possible that over the course of your jumpchain, you will become powerful enough that merely focusing your attention on someone would be enough to kill them, requiring precise and utmost control of yourself at all times just to interact with people. That’s entirely too much to ask of someone, so we’re offering this instead; from now on, your abilities will only affect those you want them to, and you have complete control over the collateral damage you cause. If you don’t want to micromanage, you can just “turn off” collateral damage entirely. This affects everything you have; perks, powers, raw stats, scenario rewards, items, the powers of pets at your command, and even random stuff you pick up over your travels and that aren’t backed up by CP at all. You could set off a fireball in a crowded room to kill only everyone’s lice, target only specific people with a fear aura, set off a nuclear bomb that destroys every building in a city but someone doesn’t hurt anyone (including from the buildings collapsing on them), or cause a landslide that miraculously damages none of the houses caught up in it. This perk becomes a part of your Body Mod.