Convoy of Tusks

Trample
Sever (Each card that you exile at random from your library as you cast this spell pays for {1}.)
When Convoy of Tusks enters the battlefield, for each mana spent to pay Convoy of Tusks's casting cost, bolster 1. (Choose a creature you control with the least toughness or tied for least toughness among creatures you control. Put one +1/+1 counters on that creature.)