For just one green, one white, and one blue mana, you could web-sling in anything from a Progenitus to a Jodah to an Atraxa
On top of that, his ability is great: Whenever you play a Floodborn character, each opponent chooses and discards a card
If you can resolve a delve creature, most of their tiny creatures are just going to lose the fight unless they have one of their few answers
With Sun Titan, you can bring back your fetch lands for more ramp, you can bring back your Esper Sentinel, Mother of Runes, or Night of the White Orchid
Some of these cards are commanders that will appeal to niche groups, while others will find their place elsewhere
If the equipped creature is dealt lethal damage at the same time that you gain life, it will die before Excalibur II's first ability would resolve