At the beginning of combat on your turn, you may pay . When you do, put a +1/+1 counter on target creature. That creature gains trample until end of turn. (It can deal excess combat damage to the player or planeswalker it’s attacking.)
"Drive the beasts into the enemy ranks, then stay back and let them do the work."
—Koth
You don't choose a target for Spiked Tyrranax's ability at the time it triggers. Rather, a second "reflexive" ability triggers when you pay {2}{G} this way. You choose a target for that ability as it goes on the stack. Each player may respond to this triggered ability as normal.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.