3 comps
AShadowplay / Drain (Shadow Priest / Lock / Shaman)
Shadowplay is the definitive TBC attrition comp: a Shadow Priest and Affliction Warlock blanket all three enemies in DoTs while Mana Burn bleeds the healer white, and a Resto Shaman makes the trio nearly unkillable. You don't burst anyone down — you fear, drain, and rot until the enemy healer is out of mana and the whole team collapses at once.
B5s Double-Healer Control
The attrition archetype: a healer-heavy core with a warrior + mage for pressure and CC. You almost never lose a teammate first and grind the enemy out — but you need a real kill condition to close, not just survive.
CDouble-Healer Hunter (Hunter / Priest / Druid)
A defensive fortress built to win the long game. Two healers keep everyone standing while the hunter drains mana with Viper Sting and traps the enemy out of every kill window. You don't burst teams down — you starve them out and grind until they crack.