-- Get the active ship data
UPDATE
	#ship_stats
SET
	actives = COUNT(*),
	duras = SUM(fc.durability)
FROM
	crawler_flsCombatant fc
WHERE
	cluster_id = fc.clusterID AND
	ship_name = fc.deedName

-- First of all, you have aggregates in an update statement which doesn't quite make sense
-- Also, I try not to write sql without aliasing the tables
-- So the intermediate (still invalid) form would apparently be:
-- ps yo' style is uggs

UPDATE	ss

SET	ss.actives = COUNT(*),
	ss.duras = SUM(fc.durability)

FROM	#ship_stats ss
	inner join crawler_flsCombatant fc on fc.clusterID = ss.cluster_id
						and fc.deedName = ss.ship_name


-- but of course, aggregates in the update still
-- a couple ways to approach this, the simplest is just subqueries
-- without actually an instance of sql server to test this, I think it's correct

update	ss set ss.actives = (select count(*)
                             from   crawler_flsCombatant fc
                             where  fc.cluster_id = ss.cluster_id
                                    and fc.deedName = ss.ship_name),
               ss.duras = (select sum(fc.durability)
                            from   crawler_flsCombatant fc
                            where  fc.cluster_id = ss.cluster_id
                                   and fc.deedName = ss.ship_name)
from	#ship_stats ss