Martyr's Soul

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
When Martyr's Soul enters, if you control no tapped lands, put two +1/+1 counters on it.

Gearseeker Serpent

This spell costs {1} less to cast for each artifact you control.
{5}{U}: Gearseeker Serpent can't be blocked this turn.

Warlord's Elite

As an additional cost to cast this spell, tap two untapped artifacts, creatures, and/or lands you control.

Writhing Necromass

This spell costs {1} less to cast for each creature card in your graveyard.
Deathtouch

Sea Gate Colossus

This spell costs {1} less to cast for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Gurmag Angler

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)

Bone Picker

This spell costs {3} less to cast if a creature died this turn.
Flying, deathtouch

Marshmist Titan

This spell costs {X} less to cast, where X is your devotion to black. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Molten Monstrosity

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
Trample

Argivian Phalanx

This spell costs {1} less to cast for each creature you control.
Vigilance (Attacking doesn't cause this creature to tap.)

Brine Giant

This spell costs {1} less to cast for each enchantment you control.

Daybreak Chimera

This spell costs {X} less to cast, where X is your devotion to white. (Each {W} in the mana costs of permanents you control counts toward your devotion to white.)
Flying