~
I'll assume he maxed mage, mastery, and lower res, and possibly revive at level 1 {possibly more for increased offense if he knows what to summon in a duel
}.
Theres not much else you can really do to increase your summon damage, but you can aid them by throwing out some spells of your own. Spear comes to mind, since it is a fairly quick offensive attack, and with moderate +skills you can get some half *** damage out of there. Spirit might help if someone is running from you and you cant seem to catch them.
Also corpse explode would be greatly augmented by your lower resistance & mercenary's conviction, although using it in a duel can be tricky; its better suited for pk'ing in a pvm game
.
About those revives;
~Carver shaman in act 5 hell {usually ice caves}, have a fiarly good ice blast.
~Slingers {arreat platue / fridged highlands i think} deal fire damage with their thrown java's
~vampires everywhere throw out fire balls when having to throw an attack at fast speeds {I've noticed they elect to throw fire balls instead of meteors or fire walls when teleporting with a necromancer}
~Tainted lighting balls can be quite painful, these can be easily found in the city of the damned and in some cold cellars in act 5.
~zakarum preists have lighting & blizzard, although the blizzard is a rareity. You can find these guys in nilithaks temple on the level with the way point about 50% of the time {every other game}, but collecting them is rare since you have to take out a horde of zealots just to get two preists.
edits; I've never really seen black souls hurt that much in a duel, mostly due to stacked lighting resistance on duelers. But for some reason, tainted still seem to pack a fairly good punch; they most likely have very high min damage.
