High-Elf Templar

Whenever a green creature enters
the battlefield under your control
put a +1/+1 counter on High-Elf Templar.
If you control another white creature,
each opponent cannot cast more than 1 spell
per turn.
If one or more -1/-1 counters would be put
on a creature you control, that many -1/-1
counters minus one are put on it instead.