If I Conceal a Shieldbearer, how will that resolve when my opponent attacks? You must attack Shieldbearer because of Taunt but the opponent can't target him for attacks etc.Will this mean I have a permanent tank until my opponent plays some AoE effect?
Taunt does not apply to stealthed minions. When your Shieldbearer attacks to reveal himself, taunt will then take effect again. However, since Shieldbearer has an attack of 0 by default, if you stealth him at that value, he will never be able to attack, and thus will remained permanently stealthed unless destroyed by an aoe or random target spell.