Slinza, the Spiked Stampede

If Slinza enters at the same time as one or more other creatures with power 4 or greater, its last ability triggers once for each of those other creatures, plus one more time for itself.

Slinza's first ability can't reduce the amount of colored mana you pay for a spell. It reduces only the generic mana component of that spell.

You don't choose a target for Slinza's last ability at the time it triggers. Rather, a second "reflexive" ability triggers when you pay {1}{R}{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.

Slinza's last ability triggers whenever any creature with power 4 or greater enters, not just one you control.

Slinza's first ability doesn't change the mana cost or mana value of any spell. It changes only the total cost you pay to cast Beast spells.

Any Beasts that enter at the same time as Slinza won't enter with an additional +1/+1 counter.