One thing that doesnt work is Frenetic Sliver as the ability states the creature must be in play for the coin flip to happen, so while you can activate it as many times as you want you can only resolve it until the creature dies
They represent Summons, creatures that are summoned to take part in battle, which are a common feature of the Final Fantasy series
Whether youre killing a board full of tokens or just one massive creature, Split Second is always a massive boon
For example, Captain Storm, Cosmium Raider from the Lost Caverns of Ixalan release has an ability that says "Whenever an artifact enters the battlefield under your control, put a +1/+1 counter on target Pirate you control." If an artifact creature enters the battlefield under your control, that ability won't trigger
When purchasing high-value cards over hundreds of dollars, always buy Graded (PSA/BGS) or from trusted sellers