It has been acknowledge as an explot/bug by the Devs.
The Generals *are not* balanced around 24 normal minions, that are balanced around 6.
Particularly with Sedna, with her aura-based minion buffs, 8 priests is simply over the top. She has a priest healing buff, attack speed buff, and +24 hps minion buff, which combines well with the +4 hps crusader plate buff. No melee DG can deal with this; and few DGs have enough AoE to kill all those rapidly healing minions (TB, maybe). Regulus, Erebus, QoT, Sedna, Oak, and UB simply don't put out enough AoE DPS to take those priests down.
Rook/TB can, however, both are quite squishy given they have to be in melee range to AoE those priests; and if the Sedna has 4 yetis, 8 priests, and 8 archers, you *will* die. Particularly if she pounces (lvl 1 pounce) one of the AoEs.
Worse; such a Sedna is absolutely devestating when played defensively (hanging around towers). A Sedna with 8 preists/8 archers/4 yetis on Crucible in damn near invincible in the towers.