+Shoal (7)
You may exile a red card with mana value X from your hand rather than pay this spell's mana cost.
Target creature gets +X/+0 until end of turn.
You may exile a blue card with mana value X from your hand rather than pay this spell's mana cost.
Counter target spell if its mana value is X.
You may exile a green card with mana value X from your hand rather than pay this spell's mana cost.
You gain X life.
You may exile a white card with mana value X from your hand rather than pay this spell's mana cost.
The next X damage that a source of your choice would deal to you and/or creatures you control this turn is dealt to any target instead.
Constellation — Whenever an enchantment enters the battlefield under your control, you may draw a card. If you do, discard a card.
Defender
Landfall — Whenever a land enters the battlefield under your control, Shoal Serpent loses defender until end of turn.
You may exile a black card with mana value X from your hand rather than pay this spell's mana cost.
Target creature gets -X/-X until end of turn.
Gatherer works better in the Companion app!