Put simply, "split second" means "As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities." The keyword was introduced in Time Spiral (one of my favorite sets of all time)
Once Jumbo Cactuars 10,000 Needles ability triggers and resolves, you can pay the three mana to sacrifice the Cactuar to Jarad to make each opponent lose 10,000 life
Brawl Legal Vintage Legal Timeless Legal Commander Legal Pauper Not Legal Oathbreaker Legal Penny Legal Toolbox Buy This Card Notes and Rules Information for Balthier and Fran: Balthier and Fran's last ability doesn't give you any additional main phases
This ensures you can not only keep casting spells, but potentially casting multiple spells per turn
Gangrenous Goliath Rarity: Rare TYPE: Creature SUBTYPE: Zombie Giant CMC: 5 Mana cost: USD: $0.19 EUR: 0.23 TIX: 0.02 EDHREC RANK: 30954 (4/4) Tap three untapped Clerics you control: Return this card from your graveyard to your hand
Get rid of Kindred Discovery and bring in Coastal Piracy