Those will occur every two days in various modes, rewarding its winners with league-unique experience points or instant vouchs, in case a top-three-finisher hasnt obtained one previously. The format is always best of one; the conditions of winning are: First blood/First tower to win. No bottle resend allowed. No crow upgrade.
In order to find out when the next tournament is gonna be held, visit the source link regularly or contact the administration via IRC.
Links
nexuscore.org - Tournament Homepage
#NexusCore, #NexusCore.Tour - Tournament IRC channels
