Kabuto summoned Deidara during the fourth world war, but only used him to keep the Tsuchikage busy while he (Kabuto) kidnapped Yamato. He then unsummoned Deidara and has never summoned him since then.
Edo Tensei makes Deidara immortal, which allows Deidara to use the C0, a giant explosion that covers an area of 10 km diameter, several times. Kabuto could have used this to eliminate the enemy units more effectively, but why did he not do so?
closed as not constructive by SingerOfTheFall, Alenanno, кяαzєя♦, Madara Uchiha, Masked Man Dec 20 '12 at 12:12
As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. If this question can be reworded to fit the rules in the help center, please edit the question.
locked by JNat♦ Dec 5 '13 at 18:08
This question exists because it has historical significance, but it is not considered a good, on-topic question for this site so please do not use it as evidence that you can ask similar questions here. This question and its answers are frozen and cannot be changed. See the help center for guidance on writing a good question.
Read more about locked posts here.
You got your facts a bit wrong actually:
He was actually summoned later, as a part of the Special Ops Batallion (or whatever the name may be), along with Sasori and Shin. They fought against Kankurou and Sai.
In that battle, he was sealed (along with Sasori) inside Kankurou's Kuroari. This, along with the fact that Kabuto was still testing the summoned ninja (since he still allowed them to retain their personalities and fighting style), is probably the reason why he was not used more effectively.
See here for more details.
Kabuto did use him effectively. He just got captured very early into the war.