Encountered this exploit when I played BG many years ago and couldnt find a discussion. Dont know if it had ever been fixed in a patch since then.
It was possible to command a summoned creature to attack an enemy, then retreat out of line of sight before the enemy responded to the party's presence. The enemy would neither follow (if retreated fast enough) nor defend itself from a vastly inferior creature. Worked with that friendly ghoul against the basilisks in the area.