After building a PvM Skellie-mance, I'm happy with my skill point lay-out, but Im still not totally set one which merc to use.
I've come to the conclusion that an Act 1 Merc with Faith Bow and Bramble Armor is ideal for the two auras they provide.

Any thoughts? or am I completely on the wrong track here...?

guide in the stickies.
stickies http://forums.d2jsp.org/topic.php?t=49337226&f=87

Faith + bramble could work.
Act 2 Might merc with bramble could also work.

If you're going to use runewords for auras, I think you have some good options open to you. Just depends on your play-style. I personally use an Act 2 merc with Might, Bramble, and Insight on my summoner so I can spam revive and never worry about running out of mana.

you could go with a2 might merc, with pride (concentration) and you either make iron golem or carry a beast for fana

I considered going with a strong golem, but I decided to go skellies and revive. I know this might not actually be important, but the A1 merc is ranged, I've already got plenty of melee skellies. also, Faith give fanatacism.

I would strongly consider an Act 2 prayer merc with an infinity.

Boost your mages attack and lessen the 're-summon' rate with the life gained from prayer.

i would say a2 might merc. combine this with amplify damage and your skeles will be doing 4x their regular dmg. on bosses this will pwn

might merc w/ infinity treach andys face

PS thorns is pretty much ineffective in hell mode. Consider you're returning 1000 points in damage. Well the beast has 450,000 life, and phys resistances. Ineffective.

Are you talking about bosses? or all monsters?

Oh no
I used to run meph all the time with summoner and thorns helped out a ton
I liked A2 with might + bramble + Infinity
Dont forget that conviction lowers defense too