Training Grounds

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Tazri, Stalwart Survivor

Each creature you control has "{T}: Add one mana of any of this creature's colors. Spend this mana only to activate an ability of a creature. Activate only if this creature has another activated ability."
{W}{U}{B}{R}{G}, {T}: Mill five cards. Put all creature cards with activated abilities that aren't mana abilities from among the milled cards into your hand.

Professor Hojo

The first activated ability you activate during your turn that targets a creature you control costs {2} less to activate.
Whenever one or more creatures you control become the target of an activated ability, draw a card. This ability triggers only once each turn.

Zirda, the Dawnwaker

Companion — Each permanent card in your starting deck has an activated ability. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
Abilities you activate that aren't mana abilities cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{1}, {T}: Target creature can't block this turn.