Run-down of Wisp's abilities and basis of build
Wisp's Reservoir ability is the backbone of her warframe. Between the stun and health/heal bonus, proper mote building can lead to near invincibility for [Wisp] and your teammates. This build maximizes the buffs while still keeping a long duration to minimize trips back to the reservoirs. Additionally, this build allows for decently easy spy runs in missions. By using her second ability, Will-O-[Wisp], you can become invisible and teleport. This allows [Wisp] to sneak past enemies, cameras and lasers. Breach surge damages enemies and inflicts radiation damage on them. They will attack other enemies and have a chance to spark which will increase damage you deal to them, as well as damage from Sol Gate. By increasing damage and duration, Wisp can prolong her Sol Gate up-time. Although I don't use this ability, it is a quick way of dealing mass damage to multiple enemies.

Tips and modifications to build
Of course, this build is open to any changes you want. Since I kept the 3 corrupted mods ([Blind Rage], [Narrow Minded] and [Transient Fortitude]) at rank 8 to keep the endo and credit cost low, you are welcome to max them out. For more ability strength, you can add a Madurai forma to half the cost of [Transient Fortitude] and add [Power Drift] to the exilus slot. Additionally, you can add whatever arcanes you see fit. As a relatively new player, I tend to not use arcanes and do not have easy access to them.

Practical use and mission types [Wisp] succeeds in
[Wisp] is great for any infinite mission, especially defense and excavation. Her mote buffs can affect what you are defending, causing it to shock nearby enemies and gain health and healing. As stated above, she also does well in spy missions due to the stealth granted by her passive and second ability. Although she is great for endless and defensive missions, I do not recommend her for missions where you progress through the map (such as capture or exterminate). This is because you will have to either constantly place new reservoirs around the map or go back to existing reservoirs, both of which being inconvenient. For these very quick missions or missions with large maps, I recommend a warframe that does not have stationary abilities.

Recap
This build gives [Wisp] as much ability strength and duration as possible while still having enough range and efficiency. She is a very versatile warframe who can do well in most mission types. Again, this build focuses on RESERVOIR, so some of her other abilities may seem lacking. If you are looking for a build to focus on her other abilities, please check out others.

I hope you enjoyed my build + mini-guide and if you liked it don't forget to upvote it and maybe leave a comment! I'd love to hear how well this build worked for you, as well as see how you modified it. Have fun!