As of the maintenance patch 31/8/10 Rune of Burning now transfers 100% of intelligence, magic power and magic crit to willpower, heal power and heal crit. This includes talismans and set bonuses. This makes the conqueror and invader sets viable as the stats become useful. We don't know if this change is going to be permanent yet as it seems like it is 'live' testing...
I can't speak for below tier 4, as these ranks flew by for me and I really can't remember but this guide should give you an idea of how to gear up for tier 4 as quickly as possible.
The goal of gearing up your runepriest, is to maximise your heal crit as soon as possible. When you get to around 25-30% heal crit, from gear, your proc rate for
Restorative Burst becomes quite reliable and you will be proccing
Blessing of Grungni regularly. Secondly you will want as much wounds as possible initially to keep you alive, and survive dungeon bosses (more on this later). From there you can work towards a high willpower/healpower build or high wounds, toughness, initiative or armour build for survival.
As soon as you get to T4, start joining in with organised guild oRvR warbands. This will allow you to quickly gain your Lesser and Greater wards without equipping the armour pieces. Don't forget to pick up the
quests in the zone as they award you medallions which you will need. With the medallion/crest conversion rate being reduced in 1.3.5 it can see some large challenges for players starting T4 obtaining the
Annihilator and
Conquerer sets.
Buy the Annihilator Gloves/Boots (and Conq/Invader/Warlord gloves & boots and stick in your bank) from the AH. They usually go pretty cheaply: 1-2g each. You want to get to the 4 piece bonus for
Annihilator ASAP for the 5% heal crit bonus. Ask guild leader for gold bags from zone locks. Ask in alliance if there are any gold bags for sale. If you are taking a keep ask politely for higher ranks to opt out. When you get the shoulder piece gem it with a +3% heal crit gem. Talisman for wounds until you have at least 6000 HP.
Go to any City Sieges you can. Try and get your Invader Chestpiece (as this will give you the Greater Ward later on if you can't get your Conq), or the nice heal crit gem from Stage 1. Stage 2 will drop your Warlord and you might get a nice purple staff. In Stage 3 it is polite to opt out to allow the higher realm ranks their Sovereign gear. The purple weapon is rubbish for a runepriest in Stage 3 anyway. You may be able to get the purple gear, from stage 3, to flesh out your set, from guildies/alliance/AH as it is bind on equip. This is called Overlord's. Also check guild bank for Primeval gear to fill out gaps in your armour.
Keep working on your wards in oRvR. You should be able to complete your lesser ward quickly, and soon you will be able to get 4/5 Greater. The final greater ward needs you to obtain your Conqueror or Sentinel chestpiece. Don't spend crests/medallions on Conqueror or
Invader gear, as the set bonuses and itemisation are poor for a healing runepriest.
When you are fully lesser warded, it's time to get a decent weapon. Get a group together for Bastion Stairs centre PQ. If you can get some guildlies who don't require the weapons it can take 15 minutes to complete the PQ and get the gold bag master looted to you. This will earn you
Runestaff of the Bloodmoon (34 will, 27 tough, 25 wounds and +7% heal crit). You probably want to equip this with a willpower and a wounds talisman. This weapon could last you until you get your royal weapon from scenarios.
Check the AH for Darkpromise Runesash and also pick up the Warlord or Sovereign accessory if it's going cheap.
You can now do the city instances,
Sigmar's Crypts and
Warpblade Tunnels, to work on your
Sentinel gear. Unfortunatly this set requires 5 pieces to get to the heal crit bonus, which makes it time consuming to grind. If you are lucky you might compliment your Annilator gear. I skipped this step and went straight to Lost Vale for my
Darkpromise Gear.
Lost Vale is doable with 4/5 Greater Wards. The key thing to remember is to keep bosses detaunted throughout the fight so you don't get fragged by their abilities. The same is true for
Tomb of the Vulture Lord, I did up to boss 6 with only 4/5, but it was with a strong group and required some strong play from myself. You should aim to get 3 pieces of Darkpromise gear, the belt from the AH counts, to get the heal crit bonus. Ideally you will pick up the clogs, as they have a 3% heal crit bonus. If you are lucky and get the whole set quickly it is a good one to wear, and allow you to mix it with Warlord when you get that. Otherwise 4 piece Darkpromise with 2 piece Annhilator nets you decent bonuses. At this point you should be quite competitive in T4. You may also be lucky and get the
Runestaff of the Greatbeard from LV.
Working on your jewellry I would advise getting the Land of the Dead
accessory sets which require
Silver Ankhs and Golden Scarabs. You can do the Airship PQ to try and get your Conqueror chest (for the last Greater ward) and also get a Silver Ankh. Another way of gathering ankhs is from the LOTD kill quest or by completing the LOTD quest line. If you are fully lesser warded you can do Tombs to obtain them whilst also obtaining some nice pocket items which absorb magic or melee damage. Alternatively, if you join a TOVL group, you can get the 14 or so ankhs you require from a few bosses. If no-one else needs the ankhs have the bags from bosses masterlooted to you. Gaining these accessories is a strong boost to your healing power.
From Darkpromise, the next upgrade is your
Warlord gear, keep going to city sieges and try to win stage 2. Save up your medallions by not buying Conqueror/Invader (except chest if you need it for the greater ward). Mixing this with Darkpromise 4:3 will get you 5% heal crit, 150 willpower, and 78 wounds from bonuses. Try and keep the Darkpromise Clogs and the Warlord Runecuffs as they both have nice heal crit. You might wish to stay will a full Darkpromise set as the Warlord set doesn't feature a heal crit bonus and the 6 piece bonus is poor.
From here on it's end game gear you are looking at. Try to get your
Glyph set and
Tyrant gear from Tomb of the Vulture Lord. Start working on your
Sovereign set. Grind scenarios to get your RvR weapon. I did not buy any of the lower weapons, and went straight for the Royal Weapon by buying the trophys as soon as possible. I did not get my weapon untill RR77 and I did mostly scenarios during this time. That said I did a lot of levelling during the 100% renown bonus from the EU merger. Without this I would have gotten the crests just before 76. I would suggest sacrificing the warlord weapon as although it's very nice, its a lot of extra scenarios to grind. If you do get your weapon early you will have something nice to look forward to when you hit RR75.
To sum up your progression should probably go along these lines:
- Annhilator and Runestaff of the Bloodmoon, with Overlord/Primeval or Sentinel mix.
- Annhilator and Darkpromise mix with LOTD accessories.
- Darkpromise and Warlord mix with TOVL Glyphs.
- DP/Tyrant/Warlord/Sovereign mix (depending on what you can get your hands on). Royal scenario weapon. TOVL Glyphs.
You can see a summary of all the Runepriest sets at WarDB
here.
With the changes in 1.3.6 using some Invader/Conqueror gear may be beneficial due to the conversion of int and magic crit. With only a 50% conversion you will have to look individually at any changes you make to your set as they are likely to be only marginal improvements.
Quick note, when buying talismans from the AH for your Runepriest you can now search for magic ones which tend to be a lot cheaper and more readily available. 
