  The large number of moduli fields arising in a generic string theory
compactification makes a complete computation of the low energy effective
theory infeasible. A common strategy to solve this problem is to consider
Calabi-Yau manifolds with discrete symmetries, which effectively reduce the
number of moduli and make the computation of the truncated Effective Field
Theory possible. In this approach, however, the couplings (e.g., the masses) of
the truncated fields are left undetermined. In the present paper we discuss the
tree-level mass spectrum of type-IIB flux compactifications at Large Complex
Structure, focusing on models with a reduced one-dimensional complex structure
sector. We compute the tree-level spectrum for the dilaton and complex
structure moduli, \emph{including the truncated fields}, which can be expressed
entirely in terms of the known couplings of the reduced theory. We show that
the masses of this set of fields are naturally heavy at vacua consistent with
the KKLT construction, and we discuss other phenomenologically interesting
scenarios where the spectrum involves fields much lighter than the gravitino.
We also derive the probability distribution for the masses on the ensemble of
flux vacua, and show that it exhibits universal features independent of the
details of the compactification. We check our results on a large sample of flux
vacua constructed in an orientifold of the Calabi-Yau
$\mathbb{WP}^4_{[1,1,1,1,4]}$. Finally, we also discuss the conditions under
which the spectrum derived here could arise in more general compactifications.
