  Energy levels and emission spectra of $W^{25+}$ ion have been studied by
performing the large-scale relativistic configuration interaction calculations.
Configuration interaction strength is used to determine the configurations
exhibiting the largest influence on the $4f^{3}$, $4d^{9}4f^{4}$, $4f^{2}5s$,
$4f^{2}5p$, $4f^{2}5d$, $4f^{2}5f$, $4f^{2}5g$, and $4f^{2}6g$ configuration
energies. It is shown that correlation effects are crucial for the $4f^{2}5s
\rightarrow 4f^{3}$ transition which in single-configuration approach occurs
due to the weak electric octupole transitions. As well, the correlation effects
affect the $4f^{2}5d \rightarrow 4f^{3}$ transitions by increasing transition
probabilities by an order. Corona model has been used to estimate the
contribution of various transitions to the emission in a low-density electron
beam ion trap (EBIT) plasma. Modeling in 10--30 nm wavelength range produces
lines which do not form emission bands and can be observed in EBIT plasma.
