If Warwick is jungling push tower with lane. You cannot take him 1v1 even with drain.
The best thing to do vs. enemy junglers is gank him with help from teammates before the game really starts. =)
If you can't get help from teammates, be very careful but you SHOULD still grab blue/red runes when you can if ONLY to deny the enemy jungler.
When ANYONE jungles on either team wards are vital near river entrances and dragon.
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