Hi solid9,
The correct verb form to use is "held".
So, the sentence should be rendered as: " It will be held.
Analysis:
1. The sentence you provided is in the passive structure.
2. It's tense is in the simple future.
See example below:
Active Voice Passive Voice
WILL + base form of verb WILL + BE + Past Participle of Verb
They will finish the work. --------> The work will be finished by them.
3. Remember to use Past Participles in:
a. Passive sentence construction
b. Perfect tenses: has/have/had eaten
c. adjectives modifying noun : drunken master, broken promise, advanced math
Hope this helps.