public override void Execute(GameLiving living)
        {
            if (CheckPreconditions(living, DEAD | SITTING | MEZZED | STUNNED))
            {
                return;
            }
            GamePlayer caster = living as GamePlayer;

            if (caster == null)
            {
                return;
            }

            MasteryofConcentrationEffect MoCEffect = caster.EffectList.GetOfType <MasteryofConcentrationEffect>();

            if (MoCEffect != null)
            {
                MoCEffect.Cancel(false);
                return;
            }

            // Check for the RA5L on the Sorceror: he cannot cast MoC when the other is up
            ShieldOfImmunityEffect ra5l = caster.EffectList.GetOfType <ShieldOfImmunityEffect>();

            if (ra5l != null)
            {
                caster.Out.SendMessage("You cannot currently use this ability", eChatType.CT_SpellResisted, eChatLoc.CL_SystemWindow);
                return;
            }

            SendCasterSpellEffectAndCastMessage(living, 7007, true);
            foreach (GamePlayer player in caster.GetPlayersInRadius(WorldMgr.VISIBILITY_DISTANCE))
            {
                if (caster.IsWithinRadius(player, WorldMgr.INFO_DISTANCE))
                {
                    if (player == caster)
                    {
                        player.MessageToSelf("You cast " + this.Name + "!", eChatType.CT_Spell);
                        player.MessageToSelf("You become steadier in your casting abilities!", eChatType.CT_Spell);
                    }
                    else
                    {
                        player.MessageFromArea(caster, caster.Name + " casts a spell!", eChatType.CT_Spell, eChatLoc.CL_SystemWindow);
                        player.Out.SendMessage(caster.Name + "'s castings have perfect poise!", eChatType.CT_System, eChatLoc.CL_SystemWindow);
                    }
                }
            }

            DisableSkill(living);

            new MasteryofConcentrationEffect().Start(caster);
        }