BOSS仇恨转移：伤害最高者实时拉走仇恨

local function firstHit(actor)
    bossTarget = actor            -- 锁死首刀，仇恨永不动
end

local AGGRO, bossTarget = {}, nil
local function onHit(actor, dmg)
    AGGRO[actor] = (AGGRO[actor] or 0) + dmg
    local top, tv = nil, 0
    for a, v in pairs(AGGRO) do
        if v > tv then top, tv = a, v end
    end
    if top ~= bossTarget then
        bossTarget = top
        sendmsg(actor, 1, "祖玛教主转向攻击伤害最高者")
    end
end