Nodetool version

version - Displays the Apache Cassandra version which your version of Scylla is most compatible with, not your current Scylla version. To display the Scylla version, refer to Check your current version of Scylla. To display additional compatibility metrics, such as CQL spec version, refer to SHOW VERSION.

For example:

nodetool version

Returns (your results may be different):

ReleaseVersion: 3.0.8

Nodetool Reference